CVE-2008-3533 in yelp
Summary
by MITRE
Format string vulnerability in the window_error function in yelp-window.c in yelp in Gnome after 2.19.90 and before 2.24 allows remote attackers to execute arbitrary code via format string specifiers in an invalid URI on the command line, as demonstrated by use of yelp within (1) man or (2) ghelp URI handlers in Firefox, Evolution, and unspecified other programs.
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Analysis
by VulDB Data Team • 12/25/2024
The CVE-2008-3533 vulnerability represents a critical format string vulnerability within the yelp document viewer component of the GNOME desktop environment. This flaw exists in the window_error function located in the yelp-window.c source file, affecting GNOME versions released after 2.19.90 and prior to 2.24. The vulnerability stems from improper handling of user-supplied input when processing URIs, specifically in how the application processes malformed or invalid URI references passed through command line arguments.
The technical exploitation of this vulnerability occurs when applications such as Firefox, Evolution, or other programs invoke the yelp utility to handle documentation requests through man or ghelp URI schemes. When these applications pass malformed URIs containing format string specifiers to yelp, the application fails to properly sanitize or escape these inputs before passing them to printf-style functions. This oversight creates a classic format string vulnerability where attacker-controlled data can contain format specifiers that allow for arbitrary memory reads and writes, ultimately enabling remote code execution capabilities.
From an operational perspective this vulnerability presents significant risk to GNOME desktop environments as it can be leveraged through web browser plugins or email clients that invoke yelp for documentation viewing. The attack surface expands beyond the immediate yelp application to include any application that utilizes yelp as a documentation handler, making it particularly dangerous in enterprise environments where multiple applications may trigger documentation viewing. The vulnerability's impact is amplified by the fact that it can be triggered without user interaction, as demonstrated through browser-based attacks targeting man or ghelp URI handlers.
The vulnerability aligns with CWE-134 which specifically addresses format string vulnerabilities where format strings are constructed from user-controlled data. From an ATT&CK framework perspective, this represents a code injection technique that could be categorized under T1059.007 for command and script injection, with potential lateral movement capabilities through privilege escalation if the vulnerable application runs with elevated permissions. The exploitation pathway typically involves crafting malicious URIs that contain format specifiers such as %x, %s, or %n that can be used to overwrite memory locations or leak stack information.
Mitigation strategies for CVE-2008-3533 require immediate patching of affected GNOME versions to 2.24 or later, where the format string vulnerability has been addressed through proper input sanitization. Organizations should also implement network-based restrictions on URI handlers that invoke yelp, particularly in environments where untrusted web content may be accessed. Input validation mechanisms should be strengthened at the application level to ensure that all URI parameters are properly escaped before being processed by printf-style functions. Additionally, system administrators should consider disabling unnecessary URI handler associations and implementing application whitelisting policies to prevent unauthorized execution of vulnerable components. The vulnerability demonstrates the importance of proper input validation and the dangers of incorporating user-supplied data directly into format string operations, reinforcing fundamental security principles that should be applied across all software development practices.