CVE-2018-16393 in OpenSC
Summary
by MITRE
Several buffer overflows when handling responses from a Gemsafe V1 Smartcard in gemsafe_get_cert_len in libopensc/pkcs15-gemsafeV1.c in OpenSC before 0.19.0-rc1 could be used by attackers able to supply crafted smartcards to cause a denial of service (application crash) or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 05/06/2023
The vulnerability CVE-2018-16393 represents a critical buffer overflow condition within the OpenSC project's smartcard handling mechanisms, specifically affecting the gemsafe_get_cert_len function in libopensc/pkcs15-gemsafeV1.c. This flaw exists in OpenSC versions prior to 0.19.0-rc1 and demonstrates a classic security weakness where insufficient input validation allows attackers to manipulate memory structures through crafted smartcard responses. The vulnerability is particularly concerning because it operates at the middleware level where smartcard communication occurs, creating potential attack vectors that could compromise the integrity of security-sensitive applications relying on OpenSC for cryptographic operations.
The technical implementation of this vulnerability stems from inadequate bounds checking within the gemsafe_get_cert_len function when processing certificate length information returned by Gemsafe V1 Smartcards. When an attacker supplies a maliciously crafted smartcard containing oversized or malformed certificate length values, the function fails to validate the input data against predetermined buffer limits. This allows the program to write beyond allocated memory boundaries, resulting in memory corruption that can manifest as application crashes or unpredictable behavior. The flaw aligns with CWE-121, which categorizes stack-based buffer overflow conditions, and demonstrates how improper input validation can lead to memory safety violations in cryptographic middleware implementations.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as the buffer overflow condition could potentially enable more sophisticated attacks depending on the execution environment. An attacker with physical access to a system running vulnerable OpenSC software could exploit this weakness to cause system instability, leading to service interruptions that might affect authentication systems, digital signature processes, or certificate management operations. The unspecified other impacts mentioned in the CVE description suggest that under certain conditions, this vulnerability could potentially be leveraged for privilege escalation or information disclosure, particularly in environments where OpenSC is integrated with security-critical applications such as PKI infrastructure, secure authentication systems, or cryptographic token management platforms.
Mitigation strategies for CVE-2018-16393 primarily focus on upgrading to OpenSC version 0.19.0-rc1 or later, which includes proper input validation and bounds checking mechanisms for certificate length handling. Organizations should also implement network segmentation and access controls to limit physical access to systems running vulnerable smartcard readers, as the attack vector requires direct interaction with the smartcard hardware. Additionally, security monitoring should be enhanced to detect unusual smartcard communication patterns that might indicate exploitation attempts, and regular security assessments should verify that all smartcard-related components are updated to secure versions. This vulnerability demonstrates the importance of input validation in security-critical middleware and aligns with ATT&CK technique T1059.001 for command and scripting interpreter usage in exploitation scenarios, though the primary attack surface remains at the application layer through crafted smartcard responses.