CVE-2016-8615 in macOS
Summary
by MITRE
A flaw was found in curl before version 7.51. If cookie state is written into a cookie jar file that is later read back and used for subsequent requests, a malicious HTTP server can inject new cookies for arbitrary domains into said cookie jar.
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Analysis
by VulDB Data Team • 10/07/2022
The vulnerability identified as CVE-2016-8615 represents a critical cookie injection flaw within the curl command-line tool and library that has significant implications for web security and session management. This vulnerability affects curl versions prior to 7.51 and stems from improper handling of cookie jar files during the read-write cycle, creating a pathway for malicious actors to manipulate client-side cookie storage mechanisms. The flaw manifests when curl applications write cookie state to a persistent cookie jar file and subsequently read that file back to maintain session state across multiple requests, establishing a persistent attack vector that can compromise user sessions and authentication mechanisms.
The technical root cause of this vulnerability lies in the inadequate validation and sanitization of cookie data when reading from cookie jar files. When curl processes cookie jar files containing cookies from previous sessions, it fails to properly validate the domain attributes and cookie values, allowing malicious HTTP servers to inject cookies that appear to originate from arbitrary domains. This occurs because the cookie jar reading mechanism does not adequately verify the integrity of cookie data or enforce proper domain restrictions, enabling attackers to craft malicious responses that, when processed by curl, result in unauthorized cookie injection. The vulnerability is classified under CWE-20 as "Improper Input Validation" and specifically relates to improper handling of cookie data integrity, making it a prime example of how seemingly benign data persistence mechanisms can become security attack vectors.
The operational impact of CVE-2016-8615 extends beyond simple session hijacking to encompass broader security implications including authentication bypass, privilege escalation, and potential data exfiltration. When a malicious HTTP server successfully injects cookies into a client's cookie jar, it can effectively impersonate legitimate domains and gain unauthorized access to resources that would normally require proper authentication. This vulnerability particularly affects automated systems and applications that rely on curl for HTTP operations, including web scraping tools, automated testing frameworks, and security scanning utilities that maintain persistent session state. The attack surface is further expanded when considering that many curl-based applications operate with elevated privileges or access to sensitive data, making successful exploitation potentially devastating. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1566.002 for "Phishing: Spearphishing Attachment" and T1071.001 for "Application Layer Protocol: Web Protocols" as it leverages HTTP protocol mechanisms to manipulate client-side cookie storage.
Mitigation strategies for CVE-2016-8615 primarily focus on upgrading to curl version 7.51 or later where the vulnerability has been addressed through improved cookie validation and sanitization mechanisms. Organizations should conduct comprehensive inventory assessments to identify all systems and applications utilizing vulnerable curl versions, particularly those that maintain persistent cookie jar files or rely on automated HTTP operations. Additional protective measures include implementing proper file access controls on cookie jar files to prevent unauthorized modification, deploying network monitoring solutions to detect anomalous cookie injection patterns, and establishing secure coding practices for applications that interface with curl libraries. Security teams should also consider implementing cookie security headers and strict SameSite policies in their web applications to provide defense-in-depth against similar cookie-related vulnerabilities. The remediation process should include thorough testing of updated curl versions in development and staging environments to ensure compatibility with existing applications while maintaining security posture against this specific vulnerability.