CVE-2005-4784 in POSIX
Summary
by MITRE
Multiple buffer overflows in the POSIX readdir_r function, as used in multiple packages, allow local users to cause a denial of service and possibly execute arbitrary code via (1) a symlink attack that exploits a race condition between opendir and pathcon calls and changes the filesystem to one with a larger maximum directory-entry name length, or (2) possibly via programmer-introduced errors on operating systems with a small struct dirent, such as Solaris or BeOS, as demonstrated in packages including (a) gcj, (b) KDE, (c) libwww, (d) the Rudiments library, (e) teTeX, (f) xmail, (g) bfbtester, (h) ncftp, (i) netwib, (j) OpenOffice.org, (k) Pike, (l) reprepro, (m) Tcl, and (n) xgsmlib.
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Analysis
by VulDB Data Team • 08/03/2017
The vulnerability described in CVE-2005-4784 represents a critical security flaw affecting the POSIX readdir_r function implementation across multiple software packages. This issue stems from improper buffer management within directory reading operations, creating conditions where attackers can exploit memory corruption through carefully crafted filesystem manipulations. The vulnerability manifests as multiple buffer overflows that occur when the system processes directory entries, particularly affecting applications that rely on the readdir_r function for directory traversal operations. The flaw is particularly concerning because it can be leveraged to cause system instability and potentially achieve arbitrary code execution within the context of the affected applications.
The technical implementation of this vulnerability involves two primary attack vectors that exploit different aspects of the POSIX directory reading mechanism. The first vector utilizes a symlink attack that capitalizes on a race condition between opendir and pathcon calls, where an attacker manipulates the filesystem to introduce directory entries with longer name lengths than initially anticipated. This creates a scenario where the buffer allocated for directory entry processing becomes insufficient, leading to memory corruption that can result in denial of service or code execution. The second vector targets systems with constrained struct dirent structures, particularly affecting operating systems like Solaris and BeOS where the directory entry structure size is smaller than expected by the application code.
The operational impact of this vulnerability extends across numerous software packages and applications, creating widespread exposure within the computing ecosystem. Applications including gcj, KDE, libwww, and OpenOffice.org are all susceptible to this vulnerability, indicating the fundamental nature of the flaw within core system components. The attack surface is significantly broadened when considering that this vulnerability affects not just individual applications but entire software ecosystems that depend on standard POSIX library functions for directory operations. The potential for privilege escalation exists through code execution capabilities, while denial of service conditions can effectively disrupt system operations and user access to critical services.
Mitigation strategies for CVE-2005-4784 require immediate attention and systematic implementation across affected systems. The primary approach involves updating all vulnerable software packages to versions that properly handle buffer boundaries in directory reading operations, with particular emphasis on ensuring that applications validate directory entry lengths against allocated buffer sizes. System administrators should implement monitoring for unusual filesystem changes that might indicate symlink attacks, as well as verify that applications are not susceptible to race conditions during directory access operations. Security patches should address both the race condition exploitation and the buffer overflow conditions, with additional measures including input validation for directory entry names and proper error handling for filesystem operations. This vulnerability aligns with CWE-121 and CWE-125 categories related to buffer overflows and improper access to memory, and represents a significant concern within the ATT&CK framework under privilege escalation and denial of service tactics. Organizations should prioritize patch management and system hardening to prevent exploitation of these fundamental library-level vulnerabilities that affect core operating system functionality.