CVE-2016-9594 in macOS
Summary
by MITRE
curl before version 7.52.1 is vulnerable to an uninitialized random in libcurl s internal function that returns a good 32bit random value. Having a weak or virtually non-existent random value makes the operations that use it vulnerable.
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Analysis
by VulDB Data Team • 12/13/2022
The vulnerability identified as CVE-2016-9594 affects curl versions prior to 7.52.1 and represents a significant weakness in the library's random number generation capabilities. This flaw resides within libcurl's internal functions responsible for generating 32-bit random values, which are critical for various security operations including SSL/TLS session handling, cookie management, and other cryptographic functions that rely on unpredictable values. The issue stems from the use of uninitialized random values that are not properly seeded or initialized, creating a predictable entropy source that can be exploited by attackers. This weakness directly impacts the cryptographic security of applications that depend on curl for network communications and data transfer operations.
The technical implementation of this vulnerability occurs within curl's internal random number generation functions where uninitialized variables are returned as random values without proper initialization or seeding. This design flaw means that the generated random numbers contain significant predictability patterns, making them unsuitable for cryptographic operations that require high entropy. The weakness is classified under CWE-330 Use of Insufficiently Random Values, which specifically addresses the use of pseudo-random number generators that do not provide adequate entropy for security-sensitive operations. The vulnerability creates a pathway for attackers to potentially predict random values used in session identifiers, cookie generation, or other security mechanisms that rely on unpredictable data, thereby undermining the overall security posture of applications utilizing affected curl versions.
The operational impact of CVE-2016-9594 extends beyond simple random number generation failures, as it affects the fundamental security assumptions of applications that depend on curl for network operations. Attackers could potentially exploit the predictable random values to perform session hijacking, cookie manipulation, or other attacks that rely on guessing or predicting random components used in security protocols. The vulnerability affects a wide range of applications including web browsers, mobile applications, and server-side components that utilize curl for HTTP/HTTPS communications. This weakness is particularly concerning in environments where curl is used for secure communications, as it can lead to authentication bypasses, data interception, or other security breaches that compromise the confidentiality and integrity of network communications. The vulnerability aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter: PowerShell, as it represents an underlying system weakness that can be leveraged by attackers to compromise security controls.
Mitigation strategies for CVE-2016-9594 require immediate deployment of curl version 7.52.1 or later, which includes proper initialization of random number generation functions. Organizations should conduct comprehensive inventory assessments to identify all systems and applications utilizing vulnerable curl versions, particularly those handling sensitive data or implementing security controls that depend on random values. The remediation process should include not only updating curl but also verifying that applications properly handle random number generation and do not rely on potentially compromised entropy sources. Security teams should implement monitoring to detect potential exploitation attempts and establish procedures for continuous vulnerability assessment of third-party libraries. Additionally, system administrators should consider implementing network segmentation and access controls to limit the impact of potential exploitation, while maintaining regular patch management processes to ensure timely deployment of security updates. The vulnerability serves as a reminder of the critical importance of proper entropy management in cryptographic implementations and the need for thorough testing of random number generation functions in security-sensitive applications.