Affecting pooledwebsocket package, versions <0.0.18
pooledwebsocket is a Pooled Web Socket server.
Affected versions of the package are vulnerable to Directory Traversal, which may allow access to sensitive files and data on the server. For example, requesting the following url
/..%2f..%2fetc/passwd would result in
Thanks to Liang Gong for disclosing this vulnerability!
- April 24th, 2017 - Disclosed to package owner
- April 24th, 2017 - Issue acknowledged by package owner.
- April 24th, 2017 - Issue fixed and version
A Directory traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating variables that reference files with “dot-dot-slash (../)” sequences and its variations or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system including application source code, configuration and other critical system files.
Directory traversal vulnerabilities can be generally divided into two types:
- Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.
st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the
If an attacker requests the following URL from our server, it will in turn, leak the sensitive private key of the root user.
%2e is the URL encoded version of
- Writing arbitrary files: Allows the attacker to create or replace existing files.
This can be achieved using a specially crafted zip archive, that holds path traversal filenames. So when the filename gets concatenated to the target extraction folder, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.
The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicous file will result in traversing out of the target folder, ending up in
/root/.ssh/ overwriting the
2018-04-15 22:04:29 ..... 19 19 good.txt 2018-04-15 22:04:42 ..... 20 20 ../../../../../../root/.ssh/authorized_keys
pooledwebsocket to version 0.0.18 or higher.