CVE-2019-12904 in Libgcrypt
Summary
by MITRE
In Libgcrypt 1.8.4, the C implementation of AES is vulnerable to a flush-and-reload side-channel attack because physical addresses are available to other processes. (The C implementation is used on platforms where an assembly-language implementation is unavailable.)
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2019-12904 affects Libgcrypt version 1.8.4 and represents a significant side-channel attack surface within the cryptographic library's implementation of the Advanced Encryption Standard. This weakness specifically targets the C implementation of AES which serves as a fallback mechanism for platforms lacking optimized assembly-language implementations. The vulnerability stems from the exposure of physical memory addresses to processes running on the same system, creating an avenue for attackers to exploit temporal and spatial memory access patterns to infer cryptographic keys.
The technical flaw manifests through the flush-and-reload side-channel attack methodology, where an adversary with access to the same physical system can monitor cache states to deduce information about cryptographic operations. In Libgcrypt's C implementation, the lack of proper memory address obfuscation or cache isolation means that an attacker can observe the memory access patterns of AES operations and correlate these observations with the encryption keys being processed. This vulnerability is particularly concerning because it operates at the hardware level, leveraging the fundamental architecture of modern processors where cache behavior reveals information about memory access patterns. The attack exploits the fact that physical addresses remain accessible to other processes, violating the principle of memory isolation that cryptographic implementations typically assume.
The operational impact of this vulnerability extends beyond simple key recovery, as it fundamentally undermines the security assumptions of the cryptographic library. Attackers can potentially extract cryptographic keys from systems running Libgcrypt 1.8.4, compromising the confidentiality of encrypted data and potentially enabling further attacks against systems that rely on this library for security. The vulnerability affects systems where the C implementation is actively used, which typically includes platforms without specialized cryptographic instructions or assembly optimizations. This creates a substantial attack surface across various computing environments where Libgcrypt is deployed for encryption, digital signatures, and key management operations.
Mitigation strategies for CVE-2019-12904 require both immediate and long-term approaches to address the underlying cache side-channel vulnerability. The most direct solution involves upgrading to a newer version of Libgcrypt that implements proper cache timing protections or uses assembly-language implementations where available. Organizations should also consider implementing memory access randomization techniques and ensuring that cryptographic operations are isolated from other processes through proper system configuration. The vulnerability aligns with CWE-310, which addresses cryptographic weakness in the use of memory addresses, and relates to ATT&CK technique T1006, which covers credential access through cache timing attacks. System administrators should also implement monitoring for suspicious memory access patterns and consider deploying hardware security modules or trusted execution environments to provide additional isolation for cryptographic operations.