CVE-2012-4424 in C Library
Summary
by MITRE
Stack-based buffer overflow in string/strcoll_l.c in the GNU C Library (aka glibc or libc6) 2.17 and earlier allows context-dependent attackers to cause a denial of service (crash) or possibly execute arbitrary code via a long string that triggers a malloc failure and use of the alloca function.
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Analysis
by VulDB Data Team • 05/26/2021
The vulnerability identified as CVE-2012-4424 represents a critical stack-based buffer overflow within the GNU C Library implementation of the strcoll_l function. This flaw exists in glibc versions 2.17 and earlier, where the library fails to properly validate string lengths during locale-aware string comparison operations. The vulnerability manifests when processing exceptionally long strings that trigger memory allocation failures, subsequently leading to improper memory management through the alloca function usage. The flaw resides in the string/strcoll_l.c source file, making it particularly dangerous as it affects fundamental string handling operations that are extensively used throughout Unix-like systems and applications.
The technical exploitation of this vulnerability occurs through a specific sequence of memory operations that leverage the interaction between malloc failure conditions and the alloca function. When a maliciously crafted long string is processed by strcoll_l, the function attempts to allocate memory on the stack using alloca, but due to the excessive string length and potential malloc failure, this operation can overflow the stack buffer. This behavior creates a condition where the stack can be overwritten with attacker-controlled data, potentially leading to arbitrary code execution or system crashes. The vulnerability is context-dependent because it requires specific conditions to be met, including the presence of locale-specific string operations and the particular memory allocation patterns that occur during processing.
From an operational perspective, this vulnerability poses significant risks to system stability and security across numerous applications that rely on glibc for string operations. The denial of service aspect can cause critical system services to crash, while the potential for arbitrary code execution makes this a severe threat to system integrity. Attackers can exploit this vulnerability through applications that perform locale-aware string comparisons, such as web servers, database systems, and network services that process user input. The impact extends beyond individual applications to potentially affect entire operating system components that depend on glibc for their string handling capabilities. This vulnerability particularly affects systems running older versions of glibc where the memory management protections are insufficient to prevent the stack overflow conditions.
Mitigation strategies for CVE-2012-4424 primarily focus on immediate system updates and patches to newer glibc versions that address the memory allocation and stack buffer handling issues. System administrators should prioritize updating their glibc installations to versions 2.18 or later where the vulnerability has been resolved through improved input validation and memory management practices. Additionally, implementing proper input sanitization at application layers can provide defense-in-depth measures, though this approach is less effective than addressing the root cause in the system library. Network segmentation and application isolation can help limit the potential impact if exploitation occurs, while monitoring for unusual string processing patterns may aid in early detection of exploitation attempts. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow and can be categorized under ATT&CK technique T1059 for command and scripting interpreter usage, as exploitation may involve crafting malicious input strings to trigger the vulnerable function.