CVE-2013-2116 in GnuTLS
Summary
by MITRE
The _gnutls_ciphertext2compressed function in lib/gnutls_cipher.c in GnuTLS 2.12.23 allows remote attackers to cause a denial of service (buffer over-read and crash) via a crafted padding length. NOTE: this might be due to an incorrect fix for CVE-2013-0169.
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Analysis
by VulDB Data Team • 05/14/2021
The vulnerability identified as CVE-2013-2116 represents a critical buffer over-read flaw within the GnuTLS cryptographic library version 2.12.23. This issue specifically affects the _gnutls_ciphertext2compressed function located in the lib/gnutls_cipher.c source file, demonstrating how seemingly minor implementation errors can lead to severe operational disruptions. The vulnerability manifests when remote attackers craft malicious padding lengths that trigger improper memory access patterns, ultimately resulting in application crashes and denial of service conditions. The flaw's classification as a buffer over-read aligns with CWE-121, which addresses critical buffer overflow conditions that occur when data is read beyond allocated memory boundaries.
The technical implementation of this vulnerability stems from inadequate input validation within the cryptographic processing pipeline of GnuTLS. When the _gnutls_ciphertext2compressed function processes encrypted data with manipulated padding parameters, it fails to properly validate the padding length against expected boundaries before attempting to decompress or process the ciphertext. This oversight creates a scenario where the function reads memory locations beyond the intended buffer limits, causing unpredictable behavior and system instability. The vulnerability's potential connection to the incorrect fix for CVE-2013-0169 suggests a problematic remediation approach that introduced new instability rather than resolving the original security concern. This pattern of remediation failure demonstrates the complexity involved in cryptographic library security updates and the potential for introducing new vulnerabilities during patch development.
Operationally, this vulnerability poses significant risks to systems relying on GnuTLS for secure communications, particularly in server environments where denial of service attacks can result in widespread service disruption. Attackers can exploit this flaw by sending specially crafted TLS/SSL packets with malformed padding lengths, causing the target application to crash and potentially making it unavailable to legitimate users. The impact extends beyond simple service interruption as the vulnerability affects the fundamental security infrastructure of applications using GnuTLS, potentially compromising the integrity of secure communication channels. Organizations using affected versions of GnuTLS must consider the broader implications for their network security posture, as this vulnerability could be leveraged as part of larger attack campaigns targeting cryptographic services.
Mitigation strategies for CVE-2013-2116 require immediate patching of affected GnuTLS installations to version 2.12.24 or later, which contains the proper fix for this buffer over-read condition. System administrators should prioritize updating all affected systems and verify that the patch resolves the specific memory access violations. Network monitoring solutions should be configured to detect unusual padding patterns in TLS traffic that might indicate exploitation attempts. The vulnerability's presence in the ATT&CK framework would likely be categorized under T1499.004 for network denial of service, highlighting the importance of implementing proper input validation and memory management controls. Additionally, organizations should conduct thorough testing of patched environments to ensure that the fix does not introduce compatibility issues with existing cryptographic protocols, while also implementing robust intrusion detection systems to monitor for potential exploitation attempts.