CVE-2019-16058 in OpenSC
Summary
by MITRE
An issue was discovered in the pam_p11 component 0.2.0 and 0.3.0 for OpenSC. If a smart card creates a signature with a length longer than 256 bytes, this triggers a buffer overflow. This may be the case for RSA keys with 4096 bits depending on the signature scheme.
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Analysis
by VulDB Data Team • 12/13/2023
The vulnerability identified as CVE-2019-16058 resides within the pam_p11 component version 0.2.0 and 0.3.0 of the OpenSC project, representing a critical buffer overflow condition that compromises system security integrity. This flaw specifically manifests when a smart card generates a cryptographic signature exceeding 256 bytes in length, creating a scenario where memory allocation becomes insufficient to accommodate the extended signature data. The vulnerability is particularly concerning because it directly impacts the authentication mechanisms that rely on smart card-based public key infrastructure implementations, potentially allowing attackers to exploit the memory corruption for unauthorized system access or privilege escalation.
The technical nature of this flaw stems from inadequate input validation and buffer management within the pam_p11 authentication module. When processing cryptographic signatures from smart cards, the component fails to properly validate the length of signature data before attempting to store it in predetermined memory buffers. This represents a classic buffer overflow vulnerability that aligns with CWE-121, which describes unsafe buffer access conditions where insufficient bounds checking allows memory corruption. The specific trigger occurs with RSA keys of 4096 bits when employing certain signature schemes that produce signatures longer than the allocated 256-byte buffer, creating a direct path for memory corruption that could be exploited by malicious actors.
The operational impact of this vulnerability extends beyond simple authentication failures, as it creates potential attack vectors for privilege escalation and system compromise. When the buffer overflow occurs during signature processing, it may allow attackers to overwrite adjacent memory locations, potentially leading to arbitrary code execution within the context of the authentication service. This threat is particularly severe in environments where pam_p11 is used for critical authentication functions, as it could enable attackers to bypass authentication mechanisms entirely or gain elevated privileges on systems relying on smart card-based authentication. The vulnerability affects systems using OpenSC versions 0.2.0 and 0.3.0, making it relevant to a significant portion of deployments that depend on smart card authentication for secure access control.
Mitigation strategies for CVE-2019-16058 require immediate attention through software updates and configuration adjustments. The primary remediation involves upgrading to patched versions of OpenSC that properly handle signature lengths exceeding 256 bytes, with the vulnerability being addressed in subsequent releases. System administrators should also implement monitoring of authentication logs for unusual signature processing patterns that might indicate exploitation attempts. Additional protective measures include configuring smart card policies to limit signature scheme choices, implementing strict input validation at multiple layers of the authentication stack, and conducting thorough security assessments of systems utilizing pam_p11 components. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting authentication mechanisms through memory corruption exploits that align with T1068, which describes privilege escalation via exploitation of software vulnerabilities in authentication systems. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts.