CVE-2012-0864 in C Library
Summary
by MITRE
Integer overflow in the vfprintf function in stdio-common/vfprintf.c in glibc 2.14 and other versions allows context-dependent attackers to bypass the FORTIFY_SOURCE protection mechanism, conduct format string attacks, and write to arbitrary memory via a large number of arguments.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability identified as CVE-2012-0864 represents a critical integer overflow flaw within the glibc standard library implementation that fundamentally undermines system security mechanisms. This issue resides in the vfprintf function located in stdio-common/vfprintf.c, specifically affecting glibc version 2.14 and potentially other versions in the same release cycle. The vulnerability operates at a foundational level within the C standard library, where the format string handling mechanism fails to properly validate argument counts, creating a condition that can be exploited by malicious actors to bypass crucial security protections.
The technical exploitation of this vulnerability stems from the improper handling of integer arithmetic within the vfprintf function when processing a large number of arguments. When the function encounters an excessive number of format specifiers or arguments, the internal counters used to track argument positions and memory allocations can overflow, causing the system to misinterpret memory boundaries. This integer overflow directly affects the FORTIFY_SOURCE protection mechanism, which is designed to detect and prevent buffer overflows by adding runtime checks to functions like sprintf, snprintf, and fprintf. The exploitation occurs because the overflowed integer values cause the protection system to either disable its checks entirely or misinterpret the intended memory access patterns, allowing attackers to craft malicious format strings that can manipulate memory locations beyond the intended boundaries.
The operational impact of this vulnerability extends far beyond simple privilege escalation or denial of service scenarios, as it provides attackers with the capability to execute arbitrary code within the context of vulnerable applications. The bypass of FORTIFY_SOURCE protection creates a significant attack surface that can be leveraged to overwrite critical memory locations, manipulate program flow, or inject malicious code into running processes. This vulnerability is particularly dangerous because it operates at the library level rather than application level, meaning that any application compiled against the affected glibc version becomes potentially vulnerable, regardless of the application's own security implementation. The context-dependent nature of the attack means that exploitation requires careful crafting of format strings and argument sequences, but the potential for successful exploitation remains high given the widespread use of glibc across Linux systems.
Security professionals should consider this vulnerability in the context of CWE-190, which addresses integer overflow conditions, and its relationship to ATT&CK technique T1059.1001 for command and scripting interpreter, as the exploitation can lead to arbitrary code execution. Mitigation strategies must include immediate patching of glibc installations to versions that contain the fix for this integer overflow condition, along with implementing additional runtime protections such as stack canaries and address space layout randomization. Organizations should also consider implementing application-level protections like format string validation and argument count limiting, while monitoring for suspicious patterns in system calls that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper integer overflow handling in system libraries and highlights the need for comprehensive security testing of core system components that form the foundation of application security across entire operating system ecosystems.