CVE-2015-3148 in cURL
Summary
by MITRE
cURL and libcurl 7.10.6 through 7.41.0 does not properly re-use authenticated Negotiate connections, which allows remote attackers to connect as other users via a request.
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Analysis
by VulDB Data Team • 05/09/2022
The vulnerability identified as CVE-2015-3148 affects cURL and libcurl versions ranging from 7.10.6 through 7.41.0, representing a critical authentication bypass flaw that undermines the security of network communications. This issue specifically targets the handling of authenticated Negotiate connections, which are typically used in enterprise environments leveraging Kerberos or NTLM authentication protocols. The flaw stems from improper connection re-use mechanisms that fail to properly validate authentication contexts when connections are recycled for subsequent requests.
The technical implementation of this vulnerability exploits the connection reuse functionality within the cURL library where authenticated sessions are not properly invalidated or re-authenticated when connections are returned to a connection pool. When a client establishes an authenticated connection using Negotiate authentication, the library maintains this connection for potential reuse in subsequent requests. However, the flaw allows an attacker to manipulate the connection state in such a way that a new request can be serviced by a connection that has been authenticated under a different user context, effectively enabling unauthorized access to resources that should be restricted to specific authenticated users.
From an operational impact perspective, this vulnerability creates significant risks for organizations relying on cURL-based applications for secure communications, particularly in environments where Kerberos or NTLM authentication is employed. Attackers can leverage this flaw to impersonate legitimate users and gain access to protected resources, potentially leading to data breaches, privilege escalation, and unauthorized system access. The vulnerability affects both client and server-side applications that utilize cURL for making authenticated requests, making it particularly dangerous in enterprise environments where multiple users access shared resources through authenticated connections.
The security implications of CVE-2015-3148 align with CWE-284, which addresses improper access control in software systems, and can be categorized under ATT&CK technique T1078 for valid accounts and T1566 for credential harvesting. Organizations using vulnerable versions of cURL should immediately implement mitigations including updating to patched versions, disabling connection reuse for authenticated sessions, and implementing additional authentication validation layers. The vulnerability demonstrates the critical importance of proper session management and authentication state handling in network libraries, particularly when dealing with enterprise authentication protocols that require strict context validation. Remediation efforts should focus on ensuring that connection pools properly invalidate authentication contexts when connections are recycled, preventing the reuse of authenticated sessions across different user contexts.