CVE-2017-14737 in Botan
Summary
by MITRE
A cryptographic cache-based side channel in the RSA implementation in Botan before 1.10.17, and 1.11.x and 2.x before 2.3.0, allows a local attacker to recover information about RSA secret keys, as demonstrated by CacheD. This occurs because an array is indexed with bits derived from a secret key.
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Analysis
by VulDB Data Team • 12/30/2022
The vulnerability CVE-2017-14737 represents a critical cryptographic side channel attack targeting the RSA implementation within the Botan cryptographic library. This flaw exists in versions prior to 1.10.17 and 2.3.0, affecting both the 1.11.x series and 2.0.x releases. The vulnerability stems from improper handling of secret key data during cryptographic operations, specifically through cache-based timing attacks that exploit the temporal characteristics of memory access patterns.
The technical implementation flaw occurs when the cryptographic library indexes an array using bits derived from the secret RSA key. This creates a predictable pattern in memory access behavior that can be observed and analyzed by a local attacker. The vulnerability operates on the principle that different memory access patterns consume varying amounts of time, creating timing variations that leak information about the secret key. This type of attack falls under the category of cache timing attacks, where the attacker monitors cache behavior to infer cryptographic key material. The specific mechanism involves the library's use of secret-dependent array indexing, which violates fundamental cryptographic security principles by creating observable side channels.
The operational impact of this vulnerability is severe for systems utilizing affected versions of the Botan library. A local attacker with access to the target system can potentially recover RSA private keys through careful analysis of cache behavior patterns. This compromise undermines the entire cryptographic security model, as the attacker gains access to the private key components that are supposed to remain confidential. The attack requires only local access to the target system, making it particularly dangerous in environments where local privilege escalation is possible or where attackers have already gained system-level access. The vulnerability affects any application that relies on Botan's RSA implementation, including secure communication protocols, digital signature systems, and encryption services.
Mitigation strategies for CVE-2017-14737 primarily involve upgrading to patched versions of the Botan library, specifically versions 1.10.17, 1.11.x, and 2.3.0 or later. Organizations should conduct thorough inventory checks to identify all systems using affected library versions and implement immediate upgrades. Additional protective measures include implementing constant-time algorithm implementations where possible, though this requires careful code review and modification. The vulnerability aligns with CWE-310, which categorizes cryptographic weaknesses related to improper use of cryptographic primitives and side channel attacks. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and defense evasion, as it enables attackers to obtain cryptographic keys that can be used for further system compromise. System administrators should also consider implementing monitoring solutions to detect unusual cache behavior patterns that might indicate exploitation attempts, while maintaining proper patch management protocols to prevent similar vulnerabilities from emerging in the future.