CVE-2009-4880 in glibc
Summary
by MITRE
Multiple integer overflows in the strfmon implementation in the GNU C Library (aka glibc or libc6) 2.10.1 and earlier allow context-dependent attackers to cause a denial of service (memory consumption or application crash) via a crafted format string, as demonstrated by a crafted first argument to the money_format function in PHP, a related issue to CVE-2008-1391.
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Analysis
by VulDB Data Team • 12/04/2024
The vulnerability described in CVE-2009-4880 represents a critical integer overflow flaw within the GNU C Library's strfmon implementation, affecting glibc versions 2.10.1 and earlier. This issue specifically targets the money_format function and related monetary formatting operations that rely on the strfmon family of functions for proper string formatting. The vulnerability stems from improper handling of integer values during format string processing, where attackers can manipulate input parameters to trigger arithmetic overflow conditions that lead to unpredictable behavior. The flaw exists in the underlying C library implementation that PHP and other applications use when processing monetary values, making it particularly dangerous for web applications that handle financial data or user input containing monetary formatting directives.
The technical exploitation of this vulnerability occurs through carefully crafted format strings that cause integer overflows during the calculation of buffer sizes or memory allocation requirements within the strfmon implementation. When the money_format function processes a malicious format string, the integer overflow can result in either negative buffer sizes or excessively large memory allocations that exceed system limits. This condition manifests as memory corruption or application crashes, effectively enabling a denial of service attack against systems running affected versions of glibc. The vulnerability is context-dependent because it requires specific conditions to be met, including the presence of a vulnerable application that uses the money_format function with user-controlled input, making it less straightforward to exploit than some other buffer overflow vulnerabilities but still highly impactful.
From an operational perspective, this vulnerability presents significant risks to systems that rely on monetary formatting capabilities, particularly web applications, financial services, and any software that processes user input containing monetary values. The impact extends beyond simple denial of service to potentially enable more sophisticated attacks if combined with other vulnerabilities, as memory corruption could potentially be exploited to execute arbitrary code under certain conditions. The vulnerability affects not just PHP applications but any software that depends on glibc's strfmon implementation, creating a broad attack surface across numerous system components. Security practitioners must consider this vulnerability as part of a larger threat landscape where integer overflows can lead to privilege escalation or information disclosure in systems that process untrusted input through standard library functions.
The mitigation strategy for CVE-2009-4880 primarily involves upgrading to a patched version of glibc, specifically versions 2.10.2 or later where the integer overflow conditions have been corrected through proper input validation and boundary checking. System administrators should prioritize patching affected systems, particularly those running web applications or services that handle monetary data or user input containing format strings. Additionally, input validation should be implemented at application layers to sanitize monetary formatting directives before they reach the underlying library functions. Organizations should also consider implementing network segmentation and monitoring to detect potential exploitation attempts targeting this vulnerability. This issue aligns with CWE-190, Integer Overflow or Wraparound, and maps to ATT&CK technique T1499.004, Network Denial of Service, as it enables attackers to consume system resources or cause application crashes through crafted input parameters. Regular vulnerability assessments and security updates should be maintained to prevent exploitation of similar integer overflow vulnerabilities in other system components.