CVE-2012-1573 in GnuTLS
Summary
by MITRE
gnutls_cipher.c in libgnutls in GnuTLS before 2.12.17 and 3.x before 3.0.15 does not properly handle data encrypted with a block cipher, which allows remote attackers to cause a denial of service (heap memory corruption and application crash) via a crafted record, as demonstrated by a crafted GenericBlockCipher structure.
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Analysis
by VulDB Data Team • 03/22/2021
The vulnerability identified as CVE-2012-1573 represents a critical heap memory corruption flaw within the GnuTLS library's cryptographic implementation. This issue affects versions prior to 2.12.17 and 3.x prior to 3.0.15, specifically impacting the gnutls_cipher.c component responsible for handling encrypted data operations. The flaw manifests when processing data encrypted using block cipher modes, creating a condition where malformed cryptographic records can trigger unexpected behavior in the underlying memory management system.
The technical exploitation of this vulnerability occurs through the manipulation of GenericBlockCipher structures within crafted network records. When GnuTLS processes these malformed structures, the library fails to properly validate the encrypted data boundaries and padding, leading to improper memory allocation and deallocation sequences. This improper handling results in heap memory corruption that can ultimately cause application crashes and complete denial of service conditions for systems relying on the vulnerable GnuTLS implementation. The vulnerability falls under the CWE-121 category of stack-based buffer overflow, though it manifests as heap corruption due to the nature of the memory management operations involved.
From an operational perspective, this vulnerability presents significant risks to any system utilizing GnuTLS for secure communications, including web servers, email servers, and any network services implementing TLS/SSL encryption. Attackers can exploit this weakness by sending specially crafted encrypted records to vulnerable services, causing them to crash and become unavailable to legitimate users. The impact extends beyond simple service disruption as the heap corruption can potentially lead to more severe consequences including arbitrary code execution depending on the specific system configuration and memory layout. This vulnerability particularly affects systems running older versions of OpenSSL-based applications or those directly using the vulnerable GnuTLS library components.
The mitigation strategy for CVE-2012-1573 involves immediate upgrading of affected GnuTLS installations to versions 2.12.17 or 3.0.15 and later, which contain the necessary patches to properly validate encrypted data structures. System administrators should also implement network monitoring to detect potential exploitation attempts through malformed TLS records, though this represents a reactive measure rather than a preventive solution. Organizations should conduct comprehensive vulnerability assessments to identify all systems using vulnerable GnuTLS versions and prioritize their remediation according to risk assessment criteria. The ATT&CK framework categorizes this vulnerability under the T1499.004 sub-technique of Network Denial of Service, highlighting its potential for causing service unavailability. Additionally, this vulnerability demonstrates the importance of proper input validation in cryptographic libraries and aligns with the broader security principle of defense in depth, where multiple layers of protection are required to prevent exploitation of memory corruption vulnerabilities in critical system components.