CVE-2018-8040 in Traffic Server
Summary
by MITRE
Pages that are rendered using the ESI plugin can have access to the cookie header when the plugin is configured not to allow access. This affects Apache Traffic Server (ATS) versions 6.0.0 to 6.2.2 and 7.0.0 to 7.1.3. To resolve this issue users running 6.x should upgrade to 6.2.3 or later versions and 7.x users should upgrade to 7.1.4 or later versions.
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Analysis
by VulDB Data Team • 05/06/2023
The vulnerability described in CVE-2018-8040 represents a critical security flaw within Apache Traffic Server's ESI (Edge Side Includes) plugin implementation that undermines the intended access controls for cookie data. This issue specifically affects versions of ATS within the 6.0.0 to 6.2.2 range and 7.0.0 to 7.1.3 range, creating a scenario where sensitive cookie information can be accessed by pages that should otherwise be restricted from such data access. The flaw manifests when the ESI plugin is configured to deny access to cookie headers, yet the system still permits unauthorized retrieval of this information, effectively bypassing the security controls that administrators have implemented to protect user session data and other sensitive cookies.
The technical implementation of this vulnerability stems from improper handling of cookie data within the ESI processing pipeline where the plugin fails to properly enforce access restrictions that should prevent pages from accessing cookie headers even when the configuration explicitly denies such access. This represents a classic case of insufficient input validation and access control enforcement, where the system's security mechanisms are bypassed due to a flaw in the implementation logic. The vulnerability operates at the intersection of web application security and proxy server functionality, where the ESI plugin's cookie handling logic does not properly respect the access control policies that should govern cookie data retrieval and usage within the edge computing environment.
The operational impact of this vulnerability extends beyond simple information disclosure, as cookie headers typically contain critical session management information, authentication tokens, and other sensitive data that could be exploited by malicious actors to hijack user sessions or gain unauthorized access to protected resources. Attackers could leverage this vulnerability to extract session cookies from pages that should be restricted from accessing such data, potentially leading to account takeover scenarios, privilege escalation, and unauthorized access to user accounts. The implications are particularly severe in environments where ATS serves as a critical edge component for web applications that rely on cookie-based authentication and session management, as this vulnerability could enable attackers to bypass the security controls that protect sensitive user information.
From a cybersecurity perspective, this vulnerability aligns with CWE-284 (Improper Access Control) and represents a failure in the principle of least privilege enforcement within the ATS system. The flaw demonstrates how configuration-based access controls can be circumvented through implementation-level issues, creating a path for attackers to exploit the system's intended security boundaries. Organizations using affected versions of Apache Traffic Server face significant risk of credential theft and session hijacking attacks, particularly in environments where cookie-based authentication is prevalent. The vulnerability also maps to ATT&CK technique T1566 (Phishing) and T1078 (Valid Accounts) as attackers could potentially use the extracted cookie information to impersonate legitimate users and gain unauthorized access to protected applications and services.
The recommended mitigation strategy involves immediate upgrading of affected systems to the patched versions, with 6.x users upgrading to 6.2.3 or later and 7.x users upgrading to 7.1.4 or later versions. This upgrade process should be implemented as a priority security measure, with organizations conducting thorough testing to ensure compatibility with existing configurations and application integrations. Additionally, system administrators should review and validate their ESI plugin configurations to ensure that appropriate access controls are properly enforced, and implement monitoring for any unauthorized access attempts or anomalies in cookie data handling. Organizations should also consider implementing additional security controls such as cookie flags like HttpOnly and Secure, which provide additional layers of protection even if the core vulnerability is present in the system.