CVE-2018-11406 in Symfony
Summary
by MITRE
An issue was discovered in the Security component in Symfony 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11. By default, a user's session is invalidated when the user is logged out. This behavior can be disabled through the invalidate_session option. In this case, CSRF tokens were not erased during logout which allowed for CSRF token fixation.
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Analysis
by VulDB Data Team • 03/27/2023
The vulnerability described in CVE-2018-11406 represents a critical session management flaw within the Symfony security component that affects multiple versions of the popular PHP framework. This issue stems from improper handling of cross-site request forgery protection mechanisms during user logout processes, creating a persistent security risk that could be exploited by malicious actors. The vulnerability specifically impacts applications using Symfony versions prior to the mentioned patches, where the default session invalidation behavior can be overridden through configuration options.
The technical flaw occurs when developers disable the default session invalidation behavior by setting the invalidate_session option to false. Under normal circumstances, Symfony automatically invalidates user sessions upon logout to prevent session hijacking attacks. However, when this behavior is disabled, the system fails to properly clean up cross-site request forgery tokens that were associated with the user's session. This creates a scenario where CSRF tokens remain valid even after users have logged out, allowing attackers to potentially reuse these tokens in subsequent malicious activities.
This vulnerability directly maps to CWE-384, which addresses Session Fixation issues in web applications, and aligns with ATT&CK technique T1531 related to "Modify System Image" through session manipulation. The operational impact of this flaw extends beyond simple session management concerns, as it creates a persistent vector for CSRF attacks that could be leveraged to perform unauthorized actions on behalf of authenticated users. Attackers could potentially exploit this vulnerability by first authenticating to a victim's account, then logging out while maintaining access to the CSRF token, and subsequently using that token to execute malicious requests against the application.
The security implications of this vulnerability are particularly concerning because CSRF token fixation attacks can enable attackers to perform actions that the victim is authorized to perform, potentially leading to data manipulation, unauthorized transactions, or complete account compromise. This issue affects the core security architecture of Symfony applications, as it undermines the fundamental principle that logout operations should completely sever all session-related security mechanisms. The vulnerability demonstrates a critical oversight in the framework's security design where the separation between session invalidation and CSRF token management was not properly enforced.
Organizations utilizing affected Symfony versions should immediately implement the available patches to address this vulnerability, as the risk of exploitation remains significant given the widespread adoption of the framework. The recommended mitigation strategy involves either upgrading to the patched versions of Symfony or ensuring that the invalidate_session option remains enabled in application configurations. Additionally, security teams should conduct thorough audits of their Symfony applications to identify any custom configurations that might have disabled session invalidation, as these deployments would be particularly vulnerable to CSRF token fixation attacks. The vulnerability highlights the importance of maintaining comprehensive security testing procedures that cover session management and authentication flows, particularly in frameworks where default security behaviors can be easily overridden through configuration settings.