CVE-2018-16418 in OpenSC
Summary
by MITRE
A buffer overflow when handling string concatenation in util_acl_to_str in tools/util.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.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/06/2023
The vulnerability identified as CVE-2018-16418 represents a critical buffer overflow condition within the OpenSC project's utility functions, specifically in the util_acl_to_str function located in tools/util.c. This flaw exists in OpenSC versions prior to 0.19.0-rc1 and demonstrates a classic security weakness that can be exploited through improper input handling during string concatenation operations. The buffer overflow occurs when the application processes access control list data structures that are typically associated with smartcard operations, creating a scenario where maliciously crafted smartcard data can trigger the vulnerability.
The technical implementation of this vulnerability stems from inadequate bounds checking during string manipulation operations within the utility function. When the util_acl_to_str function processes access control information, it fails to properly validate the length of input data before performing concatenation operations. This allows an attacker with the ability to supply crafted smartcard data to potentially overflow a fixed-size buffer, leading to memory corruption that can result in application crashes or more severe consequences. The vulnerability operates at the intersection of software security and hardware security, as it specifically targets the interaction between smartcard data and the OpenSC library that manages these devices.
From an operational perspective, this vulnerability creates significant risks for systems relying on OpenSC for smartcard authentication and access control management. The denial of service impact means that legitimate users could be denied access to services that depend on smartcard functionality, while the potential for unspecified other impacts suggests that attackers might be able to escalate privileges or execute arbitrary code under certain conditions. The attack vector requires an attacker to have the ability to supply crafted smartcard data, which makes this vulnerability particularly concerning in environments where physical access to smartcards is possible or where smartcards can be remotely provisioned with malicious data.
The security implications of this vulnerability align with CWE-121, which describes buffer overflow conditions in stack-based buffers, and can be mapped to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation'. Organizations using OpenSC for smartcard management should prioritize patching to version 0.19.0-rc1 or later, as this release contains the necessary fixes to prevent the buffer overflow condition. The mitigation strategy involves not only applying the software update but also implementing additional monitoring for unusual smartcard data patterns and ensuring proper input validation for all smartcard-related operations.
This vulnerability highlights the importance of robust input validation in security-critical software components that handle hardware interface data. The flaw demonstrates how seemingly benign utility functions can become attack vectors when proper bounds checking is omitted, particularly in systems that process untrusted data from physical hardware devices. The specific context of smartcard handling makes this vulnerability particularly relevant in enterprise environments where smartcard-based authentication systems are prevalent, as it can potentially compromise the integrity of access control mechanisms that rely on OpenSC for proper operation.