CVE-2017-15423 in Chrome
Summary
by MITRE
Inappropriate implementation in BoringSSL SPAKE2 in Google Chrome prior to 63.0.3239.84 allowed a remote attacker to leak the low-order bits of SHA512(password) by inspecting protocol traffic.
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Analysis
by VulDB Data Team • 05/06/2023
The vulnerability CVE-2017-15423 represents a cryptographic flaw in BoringSSL's implementation of the SPAKE2 password-authenticated key exchange protocol within Google Chrome versions prior to 63.0.3239.84. This issue stems from an inappropriate implementation approach that inadvertently exposes sensitive information through network traffic analysis. The vulnerability specifically affects the way the cryptographic protocol handles password hashing, creating a side-channel attack vector that allows remote adversaries to extract partial information about user credentials.
The technical flaw manifests in the SPAKE2 protocol implementation where the low-order bits of the SHA512 hash of the user's password become visible through protocol message inspection. This occurs because the implementation does not properly obscure the cryptographic operations involved in the key exchange process. The vulnerability falls under the category of side-channel attacks where attackers can infer information about secret values through analysis of observable data patterns in network communications. This type of vulnerability is particularly concerning as it operates at the cryptographic protocol level, affecting the fundamental security guarantees of password-based authentication mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, as it weakens the security of password-authenticated key exchange protocols that rely on SPAKE2. An attacker who can intercept network traffic between a victim and a server implementing this vulnerable protocol can potentially reconstruct portions of user passwords through careful analysis of the cryptographic handshake messages. This creates a significant risk for users who rely on password-based authentication for secure communications, particularly in scenarios where network traffic is monitored or intercepted. The vulnerability affects the confidentiality properties of the authentication process, undermining the security assurances that password-authenticated key exchange protocols are designed to provide.
The flaw demonstrates poor adherence to cryptographic implementation best practices and highlights the importance of proper side-channel resistance in cryptographic protocol implementations. According to CWE classification, this vulnerability relates to CWE-310: Cryptographic Issues, specifically involving improper implementation of cryptographic algorithms. From an ATT&CK framework perspective, this represents a technique for Credential Access through information disclosure, where adversaries can leverage network traffic analysis to extract password-related information. The vulnerability also connects to broader security principles around the principle of least privilege and the need for cryptographic implementations to be resistant to various forms of analysis that could reveal sensitive information.
Mitigation efforts for this vulnerability required updating Google Chrome to version 63.0.3239.84 or later, which included a corrected implementation of the SPAKE2 protocol that properly handles password hashing without exposing low-order bits. Organizations should ensure all affected systems are updated promptly and consider implementing additional network monitoring to detect potential exploitation attempts. The fix involved strengthening the cryptographic implementation to prevent information leakage through protocol messages while maintaining the intended functionality of the password-authenticated key exchange mechanism. Security practitioners should also review other cryptographic implementations within their environments to identify similar vulnerabilities that might expose sensitive information through side channels.