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
wireghoul/dotdotpwn - The Directory Traversal Fuzzer
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.
URL Encoding
.
%2e
/
%2f
\
%5c
Example: IPConfigure Orchid Core VMS 2.0.5 - Local File Inclusion
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.
.
%252e
/
%252f
\
%255c
Example: Spring MVC Directory Traversal Vulnerability (CVE-2018-1271)
Unicode Encoding
.
%u002e
/
%u2215
\
%u2216
Example: Openfire Administration Console - Authentication Bypass (CVE-2023-32315)
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.
.
%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
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
Example: Kyocera Printer d-COPIA253MF CVE-2020-23575
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.
Exploit
These exploits affect mechanism linked to specific technologies.
UNC Share
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.
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.
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
If your application is in a subfolder
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.
Java URL Protocol
Java's URL protocol when new URL('') is used allows the format url:URL
Path Traversal
Linux Files
Operating System and Informations
Processes
Network
Current Path
Indexing
Credentials and history
Kubernetes
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.
A list of files / paths to probe when arbitrary files can be read on a Microsoft Windows operating system: soffensive/windowsblindread
Labs
References
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