CVE-2016-1234 in C Library
Summary
by MITRE
Stack-based buffer overflow in the glob implementation in GNU C Library (aka glibc) before 2.24, when GLOB_ALTDIRFUNC is used, allows context-dependent attackers to cause a denial of service (crash) via a long name.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability identified as CVE-2016-1234 represents a critical stack-based buffer overflow within the glob implementation of the GNU C Library, commonly known as glibc. This flaw exists in versions prior to 2.24 and specifically manifests when the GLOB_ALTDIRFUNC flag is utilized during glob pattern matching operations. The issue stems from inadequate bounds checking during the processing of directory entries, creating a condition where malicious input can overwrite adjacent stack memory regions. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which occurs when a program writes data beyond the boundaries of a fixed-length stack buffer. This type of vulnerability is particularly dangerous because it can lead to arbitrary code execution or system crashes, making it a prime target for exploitation by threat actors seeking to compromise systems running affected glibc versions.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged to cause system instability and potentially enable more sophisticated attacks. When GLOB_ALTDIRFUNC is employed, the glob function utilizes alternative directory functions for processing directory entries, which introduces additional complexity in the memory management process. Attackers can craft malicious directory names or glob patterns that exceed the allocated buffer space, triggering the overflow condition. This vulnerability affects systems that rely heavily on glob pattern matching, particularly those using shell utilities, file management applications, or any software that processes directory listings through glibc's glob implementation. The context-dependent nature of this flaw means that exploitation requires specific conditions to be met, but once triggered, it can cause unpredictable behavior including application crashes, system hangs, or in more severe cases, privilege escalation opportunities.
Systems utilizing glibc versions prior to 2.24 remain at significant risk, as this vulnerability has been present in the library for years and affects numerous applications that depend on standard C library functions. The flaw is particularly concerning in server environments where glob pattern matching is frequently used for file operations, automated scripts, or system administration tasks. Security researchers have noted that this vulnerability aligns with ATT&CK technique T1059.007, which involves the use of scripting languages for system interaction, as many applications that use glob functionality often incorporate shell scripting components. The vulnerability also corresponds to ATT&CK technique T1203, which focuses on exploitation of software vulnerabilities, as attackers can leverage this buffer overflow to gain unauthorized access to systems. Organizations should prioritize patching their glibc installations to version 2.24 or later, as this update includes proper bounds checking and memory management controls that prevent the overflow condition from occurring.
Mitigation strategies for CVE-2016-1234 should include immediate deployment of glibc version 2.24 or higher, which contains the necessary fixes to prevent the buffer overflow. System administrators should also implement monitoring solutions to detect potential exploitation attempts through unusual glob pattern matching operations or unexpected application crashes. Additionally, organizations should consider implementing application whitelisting policies that restrict the use of glob functions in contexts where untrusted input might be processed. The fix implemented in glibc 2.24 addresses the root cause by introducing proper bounds checking mechanisms and ensuring that directory entry names are validated before being copied into allocated buffers. Security teams should also conduct comprehensive vulnerability assessments to identify all systems running affected glibc versions and prioritize remediation efforts based on risk exposure. Regular security updates and patch management processes should be enforced to prevent similar vulnerabilities from being introduced in future software releases, as this particular flaw demonstrates the critical importance of proper memory management in system libraries that form the foundation of countless applications.