CVE-2016-6709 in Android
Summary
by MITRE
An information disclosure vulnerability in Conscrypt and BoringSSL in Android 6.x before 2016-11-01 and 7.0 before 2016-11-01 could enable a man-in-the-middle attacker to gain access to sensitive information if a non-standard cipher suite is used by an application. This issue is rated as High because it could be used to access data without permission. Android ID: A-31081987.
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Analysis
by VulDB Data Team • 09/30/2022
The vulnerability described in CVE-2016-6709 represents a critical information disclosure flaw affecting the cryptographic libraries Conscrypt and BoringSSL within Android operating systems. This issue specifically impacts Android 6.0 (Marshmallow) versions prior to the November 2016 security patch cycle and Android 7.0 (Nougat) before the same patch timeline. The vulnerability stems from improper handling of non-standard cipher suites during TLS/SSL protocol negotiations, creating a pathway for malicious actors to exploit the cryptographic implementation and access sensitive data that should remain protected.
The technical root cause of this vulnerability lies in the insecure processing of cipher suite selection within the SSL/TLS implementation of these cryptographic libraries. When applications utilize non-standard cipher suites that deviate from the standard TLS protocol specifications, the Conscrypt and BoringSSL implementations fail to properly validate or sanitize these configurations. This weakness creates a potential information disclosure channel where an attacker positioned in a man-in-the-middle position can manipulate the cryptographic handshake process to extract sensitive information. The vulnerability operates at the protocol level, specifically during the initial TLS negotiation phase where cipher suites are negotiated between client and server components.
From an operational impact perspective, this vulnerability presents a significant risk to Android applications that rely on custom or non-standard cipher suite configurations. The high severity rating reflects the potential for unauthorized data access without proper authentication or authorization, as the attacker can exploit this flaw to gain insights into encrypted communications. The vulnerability affects applications that implement custom cryptographic configurations, making it particularly concerning for enterprise applications, financial services, or any systems handling sensitive data where the use of non-standard cipher suites might be intentional for specific compatibility or performance requirements. The attack vector requires the presence of a man-in-the-middle position, but once established, the vulnerability can be leveraged to compromise data confidentiality.
The mitigation strategies for CVE-2016-6709 primarily involve applying the relevant security patches released by Google in their November 2016 security updates for both Android 6.0 and Android 7.0 operating systems. Organizations should ensure their Android devices are updated to versions that include the fixed implementations of Conscrypt and BoringSSL. Additionally, application developers should review their cryptographic implementations to avoid reliance on non-standard cipher suites where possible, as this vulnerability specifically targets such configurations. The fix addresses the underlying cryptographic library implementation to properly validate and handle cipher suite selections, preventing the information disclosure that previously occurred when non-standard suites were used. This vulnerability aligns with CWE-200, which covers "Information Exposure," and represents a specific case where cryptographic implementation weaknesses create information disclosure opportunities. The ATT&CK framework categorizes this under T1566, "Phishing," and T1071.002, "Application Layer Protocol: DNS," as attackers may exploit this weakness to gain unauthorized access to sensitive communications. Organizations should also implement network monitoring to detect unusual cipher suite usage patterns that might indicate exploitation attempts, as the vulnerability specifically targets applications that implement non-standard cryptographic configurations.