Headline
New Glibc Flaw Grants Attackers Root Access on Major Linux Distros
Malicious local attackers can obtain full root access on Linux machines by taking advantage of a newly disclosed security flaw in the GNU C library (aka glibc). Tracked as CVE-2023-6246, the heap-based buffer overflow vulnerability is rooted in glibc’s __vsyslog_internal() function, which is used by syslog() and vsyslog() for system logging purposes. It’s said to have been accidentally
Vulnerability / Endpoint Security
Malicious local attackers can obtain full root access on Linux machines by taking advantage of a newly disclosed security flaw in the GNU C library (aka glibc).
Tracked as CVE-2023-6246, the heap-based buffer overflow vulnerability is rooted in glibc’s __vsyslog_internal() function, which is used by syslog() and vsyslog() for system logging purposes. It’s said to have been accidentally introduced in August 2022 with the release of glibc 2.37.
“This flaw allows local privilege escalation, enabling an unprivileged user to gain full root access,” Saeed Abbasi, product manager of the Threat Research Unit at Qualys, said, adding it impacts major Linux distributions like Debian, Ubuntu, and Fedora.
A threat actor could exploit the flaw to obtain elevated permissions via specially crafted inputs to applications that employ these logging functions.
“Although the vulnerability requires specific conditions to be exploited (such as an unusually long argv[0] or openlog() ident argument), its impact is significant due to the widespread use of the affected library,” Abbasi noted.
The cybersecurity firm said further analysis of glibc unearthed two more flaws in the __vsyslog_internal() function (CVE-2023-6779 and CVE-2023-6780) and a third bug in the library’s qsort () function that can lead to memory corruption.
The vulnerability found in qsort() has affected all glibc versions released since 1992.
The development comes nearly four months after Qualys detailed another high-severity flaw in the same library called Looney Tunables (CVE-2023-4911, CVSS score: 7.8) that could result in privilege escalation.
“These flaws highlight the critical need for strict security measures in software development, especially for core libraries widely used across many systems and applications,” Abbasi said.
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Gentoo Linux Security Advisory 202402-1 - Multiple vulnerabilities in glibc could result in Local Privilege Escalation. Versions greater than or equal to 2.38-r10 are affected.
Ubuntu Security Notice 6620-1 - It was discovered that the GNU C Library incorrectly handled the syslog function call. A local attacker could use this issue to execute arbitrary code and possibly escalate privileges.
Qualys discovered a heap-based buffer overflow in the GNU C Library's __vsyslog_internal() function, which is called by both syslog() and vsyslog(). This vulnerability was introduced in glibc 2.37 (in August 2022).
Qualys discovered a memory corruption in the glibc's qsort() function, due to a missing bounds check. To be vulnerable, a program must call qsort() with a nontransitive comparison function (a function cmp(int a, int b) that returns (a - b), for example) and with a large number of attacker-controlled elements (to cause a malloc() failure inside qsort()). They have not tried to find such a vulnerable program in the real world. All glibc versions from at least September 1992 (glibc 1.04) to the current release (glibc 2.38) are affected, but the glibc's developers have independently discovered and patched this memory corruption in the master branch (commit b9390ba, "stdlib: Fix array bounds protection in insertion sort phase of qsort") during a recent refactoring of qsort().
Debian Linux Security Advisory 5611-1 - The Qualys Research Labs discovered several vulnerabilities in the GNU C Library's __vsyslog_internal() function (called by syslog() and vsyslog()). A heap-based buffer overflow (CVE-2023-6246), an off-by-one heap overflow (CVE-2023-6779) and an integer overflow (CVE-2023-6780) can be exploited for privilege escalation or denial of service.
By Deeba Ahmed Patch Now or Pay Later: Qsort Flaw Leaves Millions of Linux Systems Exposed. This is a post from HackRead.com Read the original post: Critical Flaws Found in GNU C Library, Major Linux Distros at Risk
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Dubbed Looney Tunables, Qualys discovered a buffer overflow vulnerability in the glibc dynamic loader's processing of the GLIBC_TUNABLES environment variable. This vulnerability was introduced in April 2021 (glibc 2.34) by commit 2ed18c.
Red Hat Security Advisory 2023-5476-01 - The glibc packages provide the standard C libraries, POSIX thread libraries, standard math libraries, and the name service cache daemon used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly. Issues addressed include buffer overflow and privilege escalation vulnerabilities.
Red Hat Security Advisory 2023-5454-01 - The glibc packages provide the standard C libraries, POSIX thread libraries, standard math libraries, and the name service cache daemon used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly. Issues addressed include buffer overflow and privilege escalation vulnerabilities.
Gentoo Linux Security Advisory 202310-3 - Multiple vulnerabilities in glibc could result in Local Privilege Escalation. Versions greater than or equal to 2.37-r7 are affected.
Ubuntu Security Notice 6409-1 - It was discovered that the GNU C Library incorrectly handled the GLIBC_TUNABLES environment variable. An attacker could possibly use this issue to perform a privilege escalation attack. It was discovered that the GNU C Library incorrectly handled certain DNS responses when the system was configured in no-aaaa mode. A remote attacker could possibly use this issue to cause the GNU C Library to crash, resulting in a denial of service. This issue only affected Ubuntu 23.04.
A new Linux security vulnerability dubbed Looney Tunables has been discovered in the GNU C library's ld.so dynamic loader that, if successfully exploited, could lead to a local privilege escalation and allow a threat actor to gain root privileges. Tracked as CVE-2023-4911 (CVSS score: 7.8), the issue is a buffer overflow that resides in the dynamic loader's processing of the GLIBC_TUNABLES
A buffer overflow was discovered in the GNU C Library's dynamic loader ld.so while processing the GLIBC_TUNABLES environment variable. This issue could allow a local attacker to use maliciously crafted GLIBC_TUNABLES environment variables when launching binaries with SUID permission to execute code with elevated privileges.