CVE-2017-16652 in Symfony
Summary
by MITRE
An issue was discovered in Symfony 2.7.x before 2.7.38, 2.8.x before 2.8.31, 3.2.x before 3.2.14, and 3.3.x before 3.3.13. DefaultAuthenticationSuccessHandler or DefaultAuthenticationFailureHandler takes the content of the _target_path parameter and generates a redirect response, but no check is performed on the path, which could be an absolute URL to an external domain. This Open redirect vulnerability can be exploited for example to mount effective phishing attacks.
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Analysis
by VulDB Data Team • 03/27/2023
The vulnerability identified as CVE-2017-16652 represents a critical open redirect flaw within the Symfony framework that affects multiple version ranges including 2.7.x before 2.7.38, 2.8.x before 2.8.31, 3.2.x before 3.2.14, and 3.3.x before 3.3.13. This security weakness resides in the DefaultAuthenticationSuccessHandler and DefaultAuthenticationFailureHandler components which are fundamental parts of Symfony's authentication mechanism. The flaw stems from the framework's failure to validate or sanitize the _target_path parameter that users can provide during authentication processes, allowing malicious actors to manipulate the redirect behavior.
The technical implementation of this vulnerability occurs when the authentication handlers process the _target_path parameter without performing any validation checks on the provided URL. When users are authenticated successfully or fail to authenticate, the framework constructs a redirect response using the value from _target_path. This parameter is typically used to determine where users should be redirected after successful login or authentication failure. However, the absence of input validation means that attackers can supply absolute URLs pointing to external domains, bypassing the intended redirect logic and potentially leading to unauthorized redirections.
The operational impact of this vulnerability is particularly severe as it enables sophisticated phishing attacks and social engineering campaigns. Attackers can craft malicious URLs that, when used as the _target_path parameter, will redirect authenticated users to attacker-controlled domains. This creates a dangerous scenario where users might be tricked into visiting fraudulent websites that appear legitimate due to the framework's redirect behavior. The vulnerability essentially provides attackers with a mechanism to establish a trust relationship between their malicious domains and the legitimate Symfony application, making phishing attacks more convincing and potentially more successful.
This vulnerability maps directly to CWE-601 Open Redirect vulnerability, which is categorized under the CWE top 25 most dangerous software weaknesses. The flaw also aligns with ATT&CK technique T1566.001 Phishing, as it enables the creation of convincing phishing campaigns that leverage the legitimate application's redirect functionality. The security implications extend beyond simple redirection as this vulnerability can be exploited to create credential harvesting attacks, where users are redirected to fake login pages that capture their authentication credentials. Additionally, the vulnerability could be combined with other attack vectors to create more sophisticated multi-stage attacks that exploit the trust relationship established by the legitimate application's redirect behavior.
Organizations using affected Symfony versions should immediately implement mitigations including input validation for all redirect parameters, implementing domain whitelisting for redirect destinations, and ensuring that authentication handlers perform proper URL validation before constructing redirect responses. The recommended approach involves validating that redirect URLs either are relative paths within the application or explicitly belong to trusted domains. This vulnerability underscores the critical importance of input validation and proper security controls in authentication mechanisms, as even seemingly minor flaws in redirect handling can have significant security implications for user safety and application integrity.