CVE-2020-5205 in Pow
Summary
by MITRE
In Pow (Hex package) before 1.0.16, the use of Plug.Session in Pow.Plug.Session is susceptible to session fixation attacks if a persistent session store is used for Plug.Session, such as Redis or a database. Cookie store, which is used in most Phoenix apps, doesn't have this vulnerability.
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Analysis
by VulDB Data Team • 03/20/2024
The vulnerability identified as CVE-2020-5205 affects the Pow authentication framework version 1.0.15 and earlier, specifically within the Pow.Plug.Session module. This issue represents a critical session management flaw that could enable attackers to exploit session fixation vulnerabilities when persistent session stores are implemented. The vulnerability is particularly concerning because it affects the underlying session handling mechanism that many applications rely upon for maintaining user authentication state across requests. Session fixation attacks occur when an attacker can manipulate a user's session identifier, potentially allowing unauthorized access to user accounts. The flaw manifests when applications utilize persistent session stores such as Redis or database backends for managing session data through Plug.Session, creating a pathway for malicious actors to hijack active user sessions.
The technical root cause of this vulnerability stems from how Pow handles session management when integrated with Plug.Session's persistent storage mechanisms. When session data is stored in external systems like Redis or databases rather than in cookies, the framework fails to properly invalidate or regenerate session identifiers during authentication processes. This allows an attacker who has obtained a valid session token to maintain access to the user account even after the user has logged in or logged out, effectively bypassing normal session lifecycle management. The vulnerability specifically impacts applications that have configured their session storage to use persistent backends, which is common in production environments where session data needs to persist across application restarts or scale across multiple server instances. The flaw does not affect applications using cookie-based session storage, which is the default configuration in most Phoenix applications and provides inherent protection against this type of attack vector.
The operational impact of CVE-2020-5205 extends beyond simple authentication bypass scenarios and represents a significant threat to application security and user privacy. Attackers can exploit this vulnerability to maintain persistent access to compromised accounts, potentially leading to data breaches, unauthorized transactions, or further exploitation of the compromised user's privileges within the application. The vulnerability is particularly dangerous in multi-tenant applications or systems where session fixation could allow attackers to impersonate legitimate users and access sensitive data or perform unauthorized operations. Organizations using Pow with persistent session stores face the risk of undetected unauthorized access to user accounts, making this vulnerability a high-priority security concern that requires immediate attention. The impact is amplified in environments where session data is shared across multiple application instances or where session management is critical for maintaining application state and user authentication integrity.
The recommended mitigation strategy involves upgrading to Pow version 1.0.16 or later, which includes the necessary fixes to address the session fixation vulnerability. Organizations should also conduct a thorough assessment of their current session storage configurations to identify whether they are using persistent backends that require immediate attention. Security teams should implement monitoring procedures to detect potential exploitation attempts and consider implementing additional session management controls such as session timeout mechanisms and regular session validation checks. The vulnerability aligns with CWE-384, which describes session fixation vulnerabilities, and maps to ATT&CK technique T1563.002 related to credential access through session hijacking. Organizations should also review their session management policies and ensure that all session identifiers are properly regenerated during authentication transitions, particularly when using external session stores. Additionally, implementing proper session lifecycle management and ensuring that session data is properly invalidated upon logout or session timeout can provide additional layers of protection against exploitation of this vulnerability.