CVE-2016-4711 in macOS
Summary
by MITRE
CCrypt in corecrypto in CommonCrypto in Apple iOS before 10 and OS X before 10.12 allows attackers to discover cleartext information by leveraging a function call that specifies the same buffer for input and output.
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Analysis
by VulDB Data Team • 09/20/2022
The vulnerability identified as CVE-2016-4711 represents a critical cryptographic flaw in Apple's CommonCrypto framework affecting iOS versions prior to 10 and OS X versions prior to 10.12. This issue resides within the CCrypt function implementation in the corecrypto module, where attackers can exploit a specific function call pattern to extract cleartext information from encrypted data. The vulnerability stems from improper handling of buffer parameters during cryptographic operations, creating a potential information disclosure risk that could compromise sensitive data processed through Apple's cryptographic libraries.
The technical implementation flaw occurs when the CCrypt function receives the same memory buffer for both input and output parameters during encryption or decryption operations. This design weakness allows attackers to manipulate the cryptographic process by providing overlapping buffer references, enabling them to observe intermediate cryptographic states or directly extract plaintext data from what should remain encrypted. The vulnerability specifically targets the corecrypto module within CommonCrypto, which serves as the foundational cryptographic framework for various Apple security services and applications. This flaw operates at the kernel level and affects the fundamental cryptographic operations that underpin Apple's security architecture.
From an operational impact perspective, this vulnerability creates significant security risks for affected Apple systems as it enables attackers to recover cleartext information from encrypted communications, stored data, or cryptographic operations. The attack vector requires minimal privileges and can be executed through malicious applications or system-level exploits that leverage the flawed buffer handling. The potential consequences include unauthorized access to sensitive user data, compromise of encrypted communications, and exposure of cryptographic keys or credentials that rely on Apple's cryptographic libraries. This vulnerability affects not only direct cryptographic operations but also any application or service that depends on Apple's CommonCrypto framework for security functions.
The flaw aligns with CWE-125, which describes out-of-bounds read vulnerabilities, and represents a specific instance of improper buffer handling that can lead to information disclosure. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and credential access through exploitation of cryptographic weaknesses. The vulnerability demonstrates a classic example of how buffer management errors can lead to information disclosure, making it particularly dangerous in environments where sensitive data processing is common. Organizations affected by this vulnerability should immediately implement patch management procedures to update to supported versions of iOS and OS X, while also reviewing applications that rely on Apple's cryptographic libraries for potential exposure. Additional mitigations include monitoring for suspicious cryptographic operations and implementing network-based detection measures to identify potential exploitation attempts.