CVE-2009-4902 in PCSC-Lite
Summary
by MITRE
Buffer overflow in the MSGFunctionDemarshall function in winscard_svc.c in the PC/SC Smart Card daemon (aka PCSCD) in MUSCLE PCSC-Lite 1.5.4 and earlier might allow local users to gain privileges via crafted SCARD_CONTROL message data, which is improperly demarshalled. NOTE: this vulnerability exists because of an incorrect fix for CVE-2010-0407.
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Analysis
by VulDB Data Team • 09/18/2021
The vulnerability identified as CVE-2009-4902 represents a critical buffer overflow condition within the PC/SC Smart Card daemon implementation known as PCSCD in the MUSCLE PCSC-Lite framework version 1.5.4 and earlier. This flaw resides specifically within the MSGFunctionDemarshall function located in the winscard_svc.c source file, which handles the demarshalling process for smart card communication protocols. The vulnerability manifests when the daemon receives crafted SCARD_CONTROL message data that is improperly processed, creating an opportunity for privilege escalation attacks. The security implications are particularly severe because the daemon typically operates with elevated privileges to manage smart card communications, making local users who can submit malicious messages capable of exploiting this weakness to gain higher system privileges.
The technical nature of this vulnerability stems from improper input validation and memory management within the demarshalling function that processes communication messages between smart card readers and applications. When the MSGFunctionDemarshall function encounters malformed SCARD_CONTROL data, it fails to properly bounds-check the incoming message parameters before copying them into fixed-size buffers. This classic buffer overflow condition occurs because the implementation does not adequately verify the size of the incoming data against the allocated buffer space, allowing attackers to overwrite adjacent memory locations. The vulnerability is particularly insidious because it leverages legitimate communication protocols while exploiting implementation flaws in the message parsing logic that should have been addressed in previous security updates.
The operational impact of CVE-2009-4902 extends beyond simple privilege escalation to potentially compromise entire smart card ecosystems that rely on PCSC-Lite for secure communication. Local attackers with access to the system can exploit this vulnerability to execute arbitrary code with the privileges of the PCSCD daemon process, which typically runs with root or system-level permissions. This creates a significant risk for systems where smart card authentication is used for security-critical applications such as financial transactions, access control systems, or secure data handling environments. The vulnerability's existence as a regression issue, being caused by an incorrect fix for CVE-2010-0407, indicates that the security community had previously identified similar problems but implemented remediation that introduced new weaknesses rather than properly addressing the root cause.
This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and reflects patterns commonly seen in the ATT&CK framework under the privilege escalation and defense evasion techniques. The attack surface is particularly concerning because it targets the core communication layer of smart card systems, where the daemon typically maintains persistent connections and handles sensitive cryptographic operations. The fact that this vulnerability was introduced by a faulty security fix demonstrates the complexity of secure software development in cryptographic systems and highlights the importance of thorough regression testing. Organizations using affected versions of PCSC-Lite should immediately implement mitigation strategies including system updates, privilege restrictions on smart card services, and network segmentation to prevent local privilege escalation attacks that could compromise critical security infrastructure relying on smart card authentication mechanisms.
The remediation of CVE-2009-4902 requires updating to PCSC-Lite versions that properly address the buffer overflow condition without introducing regressions. Security administrators should also consider implementing additional monitoring and logging of smart card daemon activities to detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of maintaining secure coding practices in system-level components that handle sensitive communications and authentication processes.