CVE-2017-5656 in CXF
Summary
by MITRE
Apache CXF's STSClient before 3.1.11 and 3.0.13 uses a flawed way of caching tokens that are associated with delegation tokens, which means that an attacker could craft a token which would return an identifer corresponding to a cached token for another user.
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability identified as CVE-2017-5656 affects Apache CXF's STSClient component, specifically versions prior to 3.1.11 and 3.0.13, presenting a critical security flaw in token management and caching mechanisms. This issue resides within the Security Token Service client implementation that handles delegation tokens, creating a scenario where improper token caching could lead to unauthorized access and privilege escalation. The flaw stems from a design weakness in how the system caches tokens associated with delegation operations, fundamentally undermining the security model of token-based authentication systems.
The technical implementation of this vulnerability involves a flawed token caching algorithm that fails to properly distinguish between different user contexts when storing and retrieving delegation tokens. When an attacker crafts a malicious token, the system's caching mechanism incorrectly maps this crafted token to an existing cached token identifier associated with a different user account. This creates a token collision scenario where the system returns the cached identifier for one user when processing a token intended for another user. The vulnerability specifically targets the STSClient's token management logic, which is responsible for handling security token exchanges in web services environments. This flaw operates at the application layer and can be exploited through carefully constructed authentication requests that manipulate the token caching behavior.
The operational impact of this vulnerability extends beyond simple authentication bypass, creating potential for privilege escalation and unauthorized access to sensitive resources. An attacker who successfully exploits this vulnerability could gain access to systems and data that belong to other users within the same service environment, effectively breaking the isolation guarantees that token-based authentication systems are designed to provide. The implications are particularly severe in enterprise environments where multiple users interact with the same security token service, as this vulnerability could enable cross-user token leakage and unauthorized access to protected resources. The attack vector requires minimal privileges and can be executed through standard web service communication patterns, making it particularly dangerous in production environments.
Mitigation strategies for CVE-2017-5656 involve immediate patching of affected Apache CXF installations to versions 3.1.11 or 3.0.13, which contain the necessary fixes for the token caching implementation. Organizations should also implement additional monitoring of token usage patterns and cache invalidation processes to detect potential exploitation attempts. The fix addresses the underlying CWE-200 vulnerability category related to exposure of sensitive information through improper token handling and caching mechanisms. Security teams should review their token management policies and implement stricter validation procedures for delegated tokens, ensuring that caching mechanisms properly validate user contexts before storing or retrieving cached tokens. This vulnerability aligns with ATT&CK technique T1550.001 for legitimate credentials and T1078.004 for valid accounts, as it exploits the legitimate token exchange mechanisms to gain unauthorized access to other user accounts through flawed token caching.