CVE-2016-4752 in macOS
Summary
by MITRE
The SecKeyDeriveFromPassword function in Apple OS X before 10.12 does not use the CF_RETURNS_RETAINED keyword, which allows attackers to obtain sensitive information from process memory by triggering key derivation.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability identified as CVE-2016-4752 resides within Apple's operating system implementation of the SecKeyDeriveFromPassword function, affecting macOS versions prior to 10.12. This flaw represents a critical memory management issue that directly impacts the security of cryptographic operations within the system. The vulnerability stems from improper memory handling within the Core Foundation framework, which is fundamental to macOS application development and security operations. When the SecKeyDeriveFromPassword function processes password-based key derivation, it fails to properly manage reference counting for the returned objects, creating opportunities for information disclosure through memory inspection techniques.
The technical root cause of this vulnerability aligns with CWE-252, which describes improper handling of return values in security-relevant functions. The absence of the CF_RETURNS_RETAINED keyword in the function implementation means that the reference counting mechanism does not properly account for the returned object's lifecycle. This creates a situation where the memory management system may prematurely release objects that are still referenced by attackers, potentially exposing sensitive cryptographic data, key material, or other confidential information stored in process memory. The flaw specifically affects the key derivation process used in cryptographic operations, making it particularly dangerous for applications that rely on password-based encryption or authentication mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential access to cryptographic keys and sensitive data that could be used for privilege escalation or further exploitation. Attackers can leverage this weakness by crafting specific inputs that trigger the key derivation function and then analyze process memory to extract information that should remain protected. This vulnerability particularly affects applications that utilize the Security framework for password-based key derivation, including but not limited to secure communication protocols, encrypted file systems, and authentication services. The attack vector requires local system access and involves manipulating memory through controlled inputs to the vulnerable function, making it a medium-severity threat that can be exploited by malicious actors with system-level privileges.
Security professionals should implement immediate mitigations by upgrading affected macOS systems to version 10.12 or later, where the vulnerability has been addressed through proper memory management implementation. Organizations should also conduct comprehensive vulnerability assessments to identify applications that may be using the vulnerable function and ensure proper memory management practices are implemented in custom code. The fix implemented by Apple addresses the underlying reference counting issue by properly incorporating the CF_RETURNS_RETAINED keyword, ensuring that objects returned by the function maintain appropriate reference counts and are not prematurely deallocated. This remediation aligns with ATT&CK technique T1059.001 for executing malicious code through system commands and T1552.001 for unsecured credentials, as the vulnerability could enable attackers to extract cryptographic material that would otherwise remain protected. System administrators should also monitor for any custom applications that might be using deprecated or vulnerable implementations of key derivation functions and ensure proper security testing is performed before deployment.