CVE-2024-45192 in libolm
Summary
by MITRE • 08/22/2024
An issue was discovered in Matrix libolm (aka Olm) through 3.2.16. Cache-timing attacks can occur due to use of base64 when decoding group session keys. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
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Analysis
by VulDB Data Team • 09/11/2024
The vulnerability identified as CVE-2024-45192 affects Matrix libolm, also known as Olm, version 3.2.16 and earlier. This cryptographic library serves as a core component in end-to-end encrypted messaging systems, particularly within the Matrix communication protocol ecosystem. The flaw manifests in the library's handling of group session key decoding processes where base64 encoding operations are employed. This specific implementation creates predictable timing patterns that can be exploited by attackers to infer sensitive cryptographic information through cache-timing attacks. The vulnerability represents a significant concern for cryptographic security since it directly impacts the confidentiality and integrity of encrypted communications.
The technical implementation flaw stems from the use of base64 decoding operations during group session key processing within the Olm library. When the library processes these cryptographic elements, the timing characteristics of the base64 decoding routine create observable variations that can be measured and analyzed. Attackers can leverage these timing discrepancies to perform cache-timing attacks that gradually reveal information about the session keys being processed. This type of vulnerability falls under the category of side-channel attacks as defined by the Common Weakness Enumeration standard CWE-385, specifically targeting timing information disclosure. The vulnerability creates a covert channel through which attackers can extract cryptographic key material by monitoring the execution timing patterns of the base64 decoding operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally compromises the security assurances provided by the end-to-end encryption. In environments where Matrix-based communication systems rely on Olm for secure messaging, this vulnerability could enable adversaries to reconstruct group session keys used for encrypting messages. The implications are particularly severe for group communications where multiple participants rely on the same session key for message encryption and decryption. This weakness undermines the core security model of the system, potentially allowing unauthorized parties to access confidential communications and undermining the trust model that end-to-end encryption is designed to provide. The attack vector requires only the ability to observe timing patterns, making it relatively accessible to determined adversaries.
While the vulnerability description notes that affected products are no longer supported by maintainers, security professionals should consider the broader implications for systems that may still be in production use. Organizations utilizing legacy implementations of Olm should conduct thorough risk assessments to determine if their systems remain exposed to this vulnerability. The recommended mitigations include immediate migration to supported versions of the library where possible, though this may not be feasible for all deployments. Alternative approaches include implementing additional cryptographic protections or using different encryption libraries altogether. Security teams should also consider monitoring for potential exploitation attempts and implementing detection measures that can identify abnormal timing patterns consistent with cache-timing attacks. Organizations should evaluate their overall cryptographic posture and ensure that all communication systems maintain support for current security standards and practices. The vulnerability demonstrates the critical importance of maintaining up-to-date cryptographic libraries and the potential risks associated with using unsupported software components in security-critical applications.