CVE-2018-14780 in Yubico-Piv
Summary
by MITRE
An out-of-bounds read issue was discovered in the Yubico-Piv 1.5.0 smartcard driver. The file lib/ykpiv.c contains the following code in the function `_ykpiv_fetch_object()`: {% highlight c %} if(sw == SW_SUCCESS) { size_t outlen; int offs = _ykpiv_get_length(data + 1, &outlen); if(offs == 0) { return YKPIV_SIZE_ERROR; } memmove(data, data + 1 + offs, outlen); *len = outlen; return YKPIV_OK; } else { return YKPIV_GENERIC_ERROR; } {% endhighlight %} -- in the end, a `memmove()` occurs with a length retrieved from APDU data. This length is not checked for whether it is outside of the APDU data retrieved. Therefore the `memmove()` could copy bytes behind the allocated data buffer into this buffer.
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Analysis
by VulDB Data Team • 05/02/2023
The vulnerability described in CVE-2018-14780 represents a critical out-of-bounds read flaw within the Yubico-Piv 1.5.0 smartcard driver, specifically within the lib/ykpiv.c file in the _ykpiv_fetch_object() function. This issue stems from inadequate input validation during the processing of smartcard communication protocols, where the driver fails to properly verify the bounds of data lengths retrieved from application protocol data units. The flaw manifests when the function processes a successful status word (SW_SUCCESS) and attempts to parse data from the smartcard response. The vulnerability is classified under CWE-129 as an insufficient input validation, specifically involving improper validation of the length parameter that determines memory operations. The code structure demonstrates a clear path where the offset calculation occurs through _ykpiv_get_length() function, which extracts a length value from the APDU data stream, but fails to validate whether this extracted length value remains within the bounds of the allocated buffer.
The operational impact of this vulnerability extends beyond simple data corruption, as it creates a potential attack surface for memory corruption exploits that could lead to arbitrary code execution or privilege escalation within the smartcard environment. When the memmove() operation executes with an unvalidated length parameter, it can copy data from beyond the intended buffer boundaries into the target memory location, potentially overwriting adjacent memory regions. This behavior aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the vulnerability could enable attackers to manipulate memory contents and potentially execute malicious code within the smartcard's processing environment. The flaw is particularly dangerous because it operates at the driver level where smartcard operations are handled, making it a prime target for attackers seeking to compromise secure authentication mechanisms that rely on these cryptographic devices.
Mitigation strategies for this vulnerability must address both the immediate code-level fix and broader security considerations within smartcard implementations. The primary remediation involves implementing proper bounds checking before any memory operations, specifically validating that the extracted length parameter from _ykpiv_get_length() does not exceed the available buffer size. This requires adding validation logic to ensure that outlen remains within acceptable limits relative to the data buffer size and the offset position. Security best practices dictate that all memory operations should include comprehensive input validation, particularly when dealing with external data sources such as smartcard responses. Organizations should implement regular security updates and patches for smartcard drivers, as well as conduct thorough code reviews focusing on memory safety practices. The vulnerability highlights the importance of following secure coding guidelines and emphasizes the need for defensive programming techniques that prevent buffer overflows and out-of-bounds memory accesses in cryptographic software implementations. Additionally, the issue demonstrates the necessity of proper error handling and validation of all external inputs in security-sensitive applications, particularly those involving hardware security modules and smartcard interfaces.