CVE-2022-25332 in OMAP L138
Summary
by MITRE • 10/25/2023
The AES implementation in the Texas Instruments OMAP L138 (secure variants), present in mask ROM, suffers from a timing side channel which can be exploited by an adversary with non-secure supervisor privileges by managing cache contents and collecting timing information for different ciphertext inputs. Using this side channel, the SK_LOAD secure kernel routine can be used to recover the Customer Encryption Key (CEK).
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Analysis
by VulDB Data Team • 11/11/2023
The vulnerability identified as CVE-2022-25332 represents a critical timing side channel attack against the Advanced Encryption Standard implementation within Texas Instruments OMAP L138 secure variants. This flaw exists in the mask ROM level implementation of the cryptographic algorithm, making it particularly concerning as it resides at the hardware level rather than in software components that could be readily updated. The OMAP L138 is a low-power, high-performance processor designed for embedded applications, where the secure variants incorporate additional cryptographic protections to safeguard sensitive data. However, this specific implementation contains a fundamental weakness that undermines its security posture.
The technical flaw manifests through a timing side channel that occurs during the execution of the SK_LOAD secure kernel routine. This routine is specifically designed to load and manage cryptographic keys within the secure domain of the processor. The vulnerability exploits the relationship between cache management and execution timing, allowing an attacker with non-secure supervisor privileges to manipulate cache contents and observe variations in processing time. The attack vector specifically targets the AES encryption implementation where different ciphertext inputs produce measurable timing variations that correlate to the secret key material. This timing information can be systematically collected and analyzed to reconstruct the Customer Encryption Key, which serves as the primary cryptographic protection mechanism for sensitive data.
The operational impact of this vulnerability extends beyond simple key recovery, as it fundamentally compromises the security model of the OMAP L138 secure variants. Attackers can leverage this weakness to bypass the intended cryptographic protections, potentially gaining access to encrypted data that should remain protected within the secure domain. The fact that this attack requires only non-secure supervisor privileges makes it particularly dangerous, as it does not require the high-privilege level access typically needed for such sophisticated attacks. The timing side channel effectively allows an attacker to perform a form of cache-based side channel analysis that maps execution time variations to key material, directly violating the security assumptions of the cryptographic implementation. This vulnerability represents a significant weakness in the processor's security architecture and can be exploited to compromise the confidentiality of encrypted data processed by the device.
Mitigation strategies for CVE-2022-25332 must address both the immediate security concerns and the underlying architectural weakness. The most effective approach involves implementing constant-time cryptographic algorithms that eliminate timing variations regardless of input data, thereby preventing the side channel attack vector. Additionally, cache management techniques such as cache randomization and memory access pattern obfuscation can be employed to disrupt the attacker's ability to correlate timing information with key material. The implementation of countermeasures should align with industry standards such as those recommended in the CWE-1107 category for timing side channels and should follow ATT&CK framework techniques related to credential access through side channel attacks. Hardware-level mitigations may include the implementation of cache coherency mechanisms that prevent cache manipulation by non-secure contexts, while software-level protections should enforce strict timing guarantees for cryptographic operations. Organizations using OMAP L138 secure variants should conduct comprehensive security assessments to identify systems vulnerable to this attack and implement appropriate defensive measures to protect against potential exploitation attempts.