CVE-2019-15946 in OpenSC
Summary
by MITRE
OpenSC before 0.20.0-rc1 has an out-of-bounds access of an ASN.1 Octet string in asn1_decode_entry in libopensc/asn1.c.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 12/13/2023
The vulnerability identified as CVE-2019-15946 represents a critical out-of-bounds memory access flaw within the OpenSC cryptographic library version prior to 0.20.0-rc1. This issue resides in the asn1_decode_entry function located within the libopensc/asn1.c source file, where improper handling of ASN.1 Octet string data structures creates a potential avenue for memory corruption attacks. The flaw manifests when the library processes malformed or specially crafted ASN.1 encoded data, specifically targeting the decoding logic for octet strings that lack proper boundary validation. This type of vulnerability falls under the Common Weakness Enumeration category CWE-125, which describes out-of-bounds read conditions where an application accesses memory beyond the boundaries of a buffer or array. The vulnerability is particularly concerning in cryptographic contexts where OpenSC is used for smart card operations, certificate management, and secure authentication processes.
The technical implementation of this vulnerability involves the ASN.1 decoding routine failing to properly validate the length of octet string elements during parsing operations. When the asn1_decode_entry function encounters an ASN.1 octet string, it attempts to read data beyond the allocated buffer boundaries without adequate bounds checking. This occurs because the function does not sufficiently validate the input parameters or the expected length of the octet string before proceeding with memory access operations. The flaw can be exploited through crafted ASN.1 structures that manipulate the length field to point beyond the actual data buffer, resulting in memory corruption that may lead to arbitrary code execution or denial of service conditions. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1059.007 for command and scripting interpreter, as it could enable attackers to manipulate cryptographic operations through memory corruption.
The operational impact of this vulnerability extends across various security-sensitive applications that rely on OpenSC for cryptographic operations including smart card communication, PKI certificate processing, and secure authentication systems. Systems using affected versions of OpenSC could be vulnerable to remote exploitation if they process untrusted ASN.1 data from external sources such as certificate authorities, smart card readers, or network protocols. The memory corruption resulting from this out-of-bounds access could lead to application crashes, data corruption, or potentially more severe consequences if attackers can leverage the flaw to execute arbitrary code within the context of the affected application. This vulnerability particularly affects environments where OpenSC is integrated into security infrastructure components such as authentication servers, certificate management systems, or smart card middleware solutions. The flaw represents a significant risk to cryptographic security foundations since it undermines the integrity of the ASN.1 parsing mechanism that is fundamental to many security protocols and certificate formats.
Mitigation strategies for CVE-2019-15946 primarily focus on upgrading to OpenSC version 0.20.0-rc1 or later, which contains the necessary patches to address the out-of-bounds access issue. Organizations should prioritize updating their OpenSC installations across all systems where smart card operations, certificate processing, or cryptographic functions are performed. Additional defensive measures include implementing input validation controls for ASN.1 data processing, deploying network segmentation to limit exposure to untrusted data sources, and monitoring for异常 behavior that might indicate exploitation attempts. Security teams should also consider implementing runtime protections such as address space layout randomization and stack canaries to mitigate potential exploitation success. The vulnerability highlights the importance of proper input validation and bounds checking in cryptographic libraries, emphasizing that even seemingly minor flaws in ASN.1 parsing can have significant security implications. Organizations should conduct thorough vulnerability assessments of their cryptographic infrastructure to identify all systems using affected OpenSC versions and ensure comprehensive remediation across their security ecosystem.