CVE-2014-0015 in cURL
Summary
by MITRE
cURL and libcurl 7.10.6 through 7.34.0, when more than one authentication method is enabled, re-uses NTLM connections, which might allow context-dependent attackers to authenticate as other users via a request.
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Analysis
by VulDB Data Team • 06/08/2021
The vulnerability identified as CVE-2014-0015 affects cURL and libcurl versions ranging from 7.10.6 through 7.34.0, presenting a significant security risk related to authentication handling within NTLM connections. This flaw stems from the improper management of authentication contexts when multiple authentication methods are enabled, creating opportunities for unauthorized authentication attempts. The vulnerability operates at the application layer and specifically targets the NTLM authentication mechanism, which is commonly used in enterprise environments for Windows authentication. The issue manifests when the system reuses existing NTLM connections without properly validating the authentication context, potentially allowing attackers to impersonate legitimate users within the authenticated session. This represents a classic case of authentication bypass vulnerability that can be exploited through context-dependent attack vectors. The flaw is particularly concerning because it leverages existing connection reuse mechanisms that are designed for performance optimization but become security risks when authentication contexts are not properly managed.
The technical implementation of this vulnerability involves the NTLM authentication protocol's connection reuse behavior within the cURL library. When multiple authentication methods are enabled, the library maintains connection state that includes authentication tokens and context information. The flaw occurs because the connection reuse logic does not adequately validate whether the current authentication context matches the intended user context. This allows an attacker to potentially manipulate the authentication state during connection reuse, effectively enabling them to authenticate as other users within the same session. The vulnerability is classified under CWE-287, which addresses improper authentication, and aligns with ATT&CK technique T1078 for Valid Accounts and T1550 for Use of Valid Accounts. The root cause lies in the insufficient separation of authentication contexts when reusing connections, particularly in environments where NTLM authentication is prevalent. The library's connection pooling mechanism fails to properly isolate authentication states, creating a path for credential theft and unauthorized access.
The operational impact of CVE-2014-0015 extends beyond simple authentication bypass to encompass potential privilege escalation and lateral movement within enterprise networks. Organizations relying on cURL for web services and API communications are at risk of unauthorized access to resources protected by NTLM authentication, including file shares, web applications, and internal services. The vulnerability can be exploited in various scenarios such as web application attacks, man-in-the-middle situations, or when attackers gain access to systems that make authenticated requests using cURL. The risk is particularly elevated in environments where NTLM authentication is used for single sign-on implementations or where connection reuse is common due to performance requirements. Attackers can leverage this vulnerability to access sensitive data, perform administrative actions, or establish persistent access to systems. The impact is amplified when combined with other vulnerabilities or when attackers can manipulate the connection reuse behavior through network-level attacks or by crafting specific requests that trigger the vulnerable code path.
Organizations should prioritize immediate remediation by upgrading to cURL version 7.35.0 or later, which contains the necessary patches to address the authentication context handling issue. The mitigation strategy should include comprehensive vulnerability scanning to identify systems running affected versions of cURL and libcurl, particularly those handling NTLM authentication. Network segmentation and monitoring should be implemented to detect anomalous authentication patterns that might indicate exploitation attempts. Security teams should also review and tighten authentication policies, ensuring that connection reuse is carefully managed and that authentication contexts are properly validated during connection establishment. Additional mitigations include implementing proper access controls, using more secure authentication mechanisms such as Kerberos instead of NTLM where possible, and establishing network-level protections against unauthorized access attempts. The vulnerability demonstrates the importance of proper state management in authentication protocols and highlights the need for careful consideration of connection reuse patterns in security-sensitive applications. Organizations should also consider implementing automated patch management processes to ensure timely updates and reduce the window of exposure to similar vulnerabilities.