CVE-2012-1569 in GnuTLS
Summary
by MITRE
The asn1_get_length_der function in decoding.c in GNU Libtasn1 before 2.12, as used in GnuTLS before 3.0.16 and other products, does not properly handle certain large length values, which allows remote attackers to cause a denial of service (heap memory corruption and application crash) or possibly have unspecified other impact via a crafted ASN.1 structure.
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Analysis
by VulDB Data Team • 12/24/2024
The vulnerability identified as CVE-2012-1569 represents a critical heap memory corruption flaw within the GNU Libtasn1 library version 2.11 and earlier, which affects the widely-used GnuTLS cryptographic library and numerous other software products that depend on ASN.1 decoding functionality. This vulnerability stems from improper handling of large length values during the decoding process, specifically within the asn1_get_length_der function located in the decoding.c source file. The flaw manifests when the library encounters crafted ASN.1 structures containing malformed length encodings that exceed normal processing boundaries, creating a condition where heap memory becomes corrupted through improper memory allocation and handling. The vulnerability falls under CWE-122, Heap-based Buffer Overflow, and specifically addresses improper handling of length fields in ASN.1 DER encoding, which is a fundamental aspect of cryptographic protocol implementations that rely on structured data formats.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more sophisticated attack vectors that could compromise system stability and availability. Remote attackers can exploit this weakness by constructing malicious ASN.1 structures with specially crafted large length values that trigger memory corruption during the decoding process. When the vulnerable library processes these structures, the improper length handling causes heap memory corruption, leading to application crashes or unpredictable behavior that can be leveraged for denial of service attacks against systems relying on affected software components. The vulnerability's potential for unspecified other impacts suggests that under certain conditions, it might provide opportunities for information disclosure, privilege escalation, or execution of arbitrary code, making it particularly dangerous in security-sensitive environments. This aligns with ATT&CK technique T1499.004, which covers network denial of service attacks that can be executed through memory corruption vulnerabilities.
Systems utilizing GnuTLS versions prior to 3.0.16, GNU Libtasn1 versions before 2.12, and any other software products that incorporate vulnerable ASN.1 decoding libraries are at risk of exploitation. The vulnerability is particularly concerning because it affects core cryptographic libraries that form the foundation of secure communications across numerous applications including web servers, email systems, and network protocols that depend on X.509 certificates and other ASN.1-encoded data structures. Organizations should prioritize patching their systems to upgrade to GnuTLS 3.0.16 or later, GNU Libtasn1 2.12 or later, and ensure that all dependent applications are updated to prevent exploitation. Additionally, implementing network segmentation, monitoring for unusual ASN.1 structure processing, and conducting thorough vulnerability assessments of all systems that process external ASN.1 data can help mitigate the risk associated with this vulnerability. The fix implemented in the patched versions addresses the improper length handling by introducing proper validation and bounds checking mechanisms that prevent the heap corruption conditions from occurring during ASN.1 structure decoding operations.