CVE-2020-15309 in wolfSSL
Summary
by MITRE
An issue was discovered in wolfSSL before 4.5.0, when single precision is not employed. Local attackers can conduct a cache-timing attack against public key operations. These attackers may already have obtained sensitive information if the affected system has been used for private key operations (e.g., signing with a private key).
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Analysis
by VulDB Data Team • 11/10/2020
This vulnerability represents a significant cryptographic weakness in the wolfSSL library affecting versions prior to 4.5.0. The issue specifically manifests when the library operates without single precision arithmetic enabled, creating an exploitable condition that allows local attackers to perform cache-timing attacks against public key operations. The vulnerability stems from the predictable timing patterns that occur during cryptographic computations, which can be observed and analyzed by adversaries with local access to the system. This type of side-channel attack exploits the relationship between the physical implementation of cryptographic algorithms and the timing information that can be gleaned from cache behavior.
The technical flaw lies in the implementation of public key cryptographic operations within wolfSSL's cryptographic engine. When single precision is disabled, the library's handling of modular exponentiation and other key operations becomes vulnerable to timing analysis. Attackers can monitor the time taken for cryptographic operations and correlate this timing data with cache access patterns to infer sensitive information about the private key being used. This vulnerability is particularly concerning because it operates at the cryptographic protocol level, affecting the fundamental security guarantees of the encryption system. The attack vector requires local access to the system since cache-timing attacks typically rely on observing memory access patterns from within the same machine, making it a local privilege escalation threat rather than a remote attack.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can compromise the entire security posture of systems relying on wolfSSL for cryptographic operations. Systems that have been used for private key operations such as digital signing, key exchange, or certificate generation become vulnerable to information leakage that could potentially allow attackers to reconstruct private keys over time. This makes the vulnerability particularly dangerous in environments where the same system performs multiple cryptographic operations with the same private key, as the cumulative timing data can provide attackers with sufficient information to break the cryptographic security. The vulnerability affects a wide range of applications including web servers, email systems, and any software that utilizes wolfSSL for secure communications, potentially leading to widespread compromise of encrypted communications.
Organizations should immediately upgrade to wolfSSL version 4.5.0 or later to address this vulnerability, as the fix implements proper countermeasures against cache-timing attacks. The recommended mitigation strategy includes enabling single precision arithmetic within the wolfSSL configuration and ensuring that all systems using the library are updated to the patched version. Additionally, security teams should monitor for any signs of exploitation attempts and consider implementing additional logging and monitoring around cryptographic operations to detect potential timing-based attacks. The vulnerability aligns with CWE-310, which covers cryptographic issues related to timing attacks, and represents a specific implementation weakness that falls under the ATT&CK technique of T1005, which involves data from local system information gathering through timing side channels. System administrators should also consider implementing cryptographic best practices such as using constant-time implementations for cryptographic operations and regularly auditing cryptographic libraries for known vulnerabilities to prevent similar issues from occurring in the future.