Linux Distributions Vulnerable – Glibc Flaw Grants Root Access to Unprivileged Users
A recently discovered local privilege escalation (LPE) vulnerability in the GNU C Library (glibc) is causing alarm in the Linux community, as it opens the door for unprivileged attackers to gain root access on default configurations of several major Linux distributions. Tracked as CVE-2023-6246, this security flaw resides in glibc’s __vsyslog_internal() function, crucially employed by widely-used syslog and vsyslog functions for logging messages to the system message logger.
The critical bug, inadvertently introduced in glibc 2.37 in August 2022 and later backported to glibc 2.36 while addressing a less severe vulnerability (CVE-2022-39046), manifests as a heap-based buffer overflow weakness. The vulnerability allows local privilege escalation, empowering an unprivileged user to attain full root access through manipulated inputs in applications utilizing these logging functions. While certain conditions must be met for exploitation, such as an unusually long argv[0] or specific openlog() ident arguments, the potential impact is substantial due to the widespread use of the affected library.
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Affected distributions
Qualys security researchers, in their testing, verified the vulnerability’s existence in Debian 12 and 13, Ubuntu 23.04 and 23.10, and Fedora 37 to 39. In these distributions, unprivileged users could exploit CVE-2023-6246 to elevate their privileges to full root access in default installations. The researchers noted that their tests were limited to a select few distros, suggesting that other distributions may also be exploitable.
The discovery of this vulnerability underscores the critical need for rigorous security measures in software development, particularly for core libraries widely utilized across numerous systems and applications.
Qualys researchers, who have previously uncovered various Linux security vulnerabilities, including those affecting glibc’s ld.so dynamic loader, Polkit’s pkexec component, the Kernel’s filesystem layer, and the Sudo Unix program, emphasize the ongoing challenges in maintaining the security of Linux systems.
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Source: bleepingcomputer.com
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