CVE-2016-1777 in macOS
Summary
by MITRE
Web Server in Apple OS X Server before 5.1 supports the RC4 algorithm, which makes it easier for remote attackers to defeat cryptographic protection mechanisms via unspecified vectors.
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Analysis
by VulDB Data Team • 10/08/2022
The vulnerability identified as CVE-2016-1777 represents a significant cryptographic weakness in Apple OS X Server versions prior to 5.1, specifically concerning the implementation of the RC4 encryption algorithm within its web server component. This issue stems from the inclusion of RC4 as a supported cipher suite, a decision that contradicts modern cryptographic best practices and industry recommendations. The RC4 algorithm, once widely deployed, has been extensively criticized and deprecated due to numerous cryptographic flaws that render it vulnerable to various attack vectors.
The technical flaw manifests in the web server's cryptographic configuration where RC4 remains enabled as a supported encryption method, creating opportunities for remote attackers to exploit weaknesses inherent in the algorithm's design. RC4 suffers from several well-documented vulnerabilities including bias in its output stream, key scheduling issues, and pattern recognition vulnerabilities that can be leveraged to compromise encrypted communications. The unspecified vectors mentioned in the CVE description likely encompass techniques such as ciphertext analysis, key recovery attacks, and protocol downgrade attacks that become more feasible when RC4 is available as a cipher option.
From an operational impact perspective, this vulnerability creates substantial risk for organizations relying on Apple OS X Server for web services, as it weakens the overall security posture of the system. Remote attackers can potentially intercept and manipulate encrypted web traffic, leading to data breaches, session hijacking, and unauthorized access to sensitive information. The vulnerability affects the confidentiality and integrity of communications between clients and the web server, undermining the fundamental security guarantees that cryptographic protocols are designed to provide. Organizations may experience regulatory compliance issues and reputational damage if attackers successfully exploit this weakness to compromise their web services.
The vulnerability aligns with CWE-327, which addresses the use of weak cryptographic algorithms, and relates to ATT&CK technique T1071.004 for application layer protocols and T1566 for credential access through social engineering or protocol manipulation. Organizations should immediately implement mitigations including disabling RC4 support in the web server configuration, upgrading to Apple OS X Server version 5.1 or later, and conducting comprehensive security assessments of their web infrastructure. Additional protective measures include implementing strong cipher suite preferences that prioritize modern algorithms such as AES-GCM, configuring proper security headers, and monitoring for suspicious network activity that might indicate exploitation attempts. The remediation process should also involve reviewing and updating cryptographic policies to ensure compliance with current security standards and regulatory requirements.