CVE-2017-1000069 in oauth2_proxy
Summary
by MITRE
CSRF in Bitly oauth2_proxy 2.1 during authentication flow
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Analysis
by VulDB Data Team • 12/12/2022
The vulnerability CVE-2017-1000069 represents a cross-site request forgery issue within the Bitly oauth2_proxy version 2.1 authentication mechanism. This flaw specifically manifests during the OAuth2 authentication flow where the application fails to properly validate request origins and lacks adequate anti-CSRF protection measures. The vulnerability resides in the authentication handler that processes OAuth2 callback requests, making it susceptible to malicious exploitation by attackers who can craft forged requests to manipulate user authentication states. The issue stems from the application's inadequate validation of the referer header and lack of proper CSRF token implementation during the OAuth2 authorization code flow. This weakness allows attackers to perform unauthorized actions on behalf of authenticated users by exploiting the trust relationship between the application and the OAuth2 provider.
The technical implementation of this vulnerability occurs when the oauth2_proxy application processes the OAuth2 callback endpoint without sufficient validation of the request context. During the authentication flow, the application receives authorization codes from the OAuth2 provider and attempts to exchange them for access tokens. However, due to insufficient CSRF protection mechanisms, an attacker can craft malicious requests that appear legitimate to the application. The vulnerability manifests when the application does not verify that the callback request originates from the expected OAuth2 provider or when it fails to validate the state parameter that should be used to prevent CSRF attacks. This flaw aligns with CWE-352, which specifically addresses Cross-Site Request Forgery vulnerabilities, and demonstrates poor implementation of the OAuth2 authorization code flow security requirements.
The operational impact of this vulnerability is significant as it can lead to unauthorized access to user accounts and potential privilege escalation within systems that rely on Bitly oauth2_proxy for authentication. An attacker could exploit this vulnerability to hijack user sessions, gain access to protected resources, or perform actions on behalf of authenticated users without their knowledge. The attack typically requires the user to be authenticated with the vulnerable application and to visit a malicious website or click on a crafted link that triggers the CSRF attack. The vulnerability can be particularly dangerous in enterprise environments where the oauth2_proxy is used to protect sensitive applications and services, as successful exploitation could result in data breaches, unauthorized system access, or lateral movement within the network infrastructure.
Mitigation strategies for CVE-2017-1000069 should focus on implementing robust CSRF protection mechanisms within the OAuth2 authentication flow. Organizations should upgrade to patched versions of oauth2_proxy that properly implement CSRF token validation and referer header checking. The implementation should include proper state parameter validation during the OAuth2 flow, ensuring that each authentication request includes a unique and unpredictable state value that is verified upon callback. Security measures should also include validating the referer header against expected domains and implementing additional authentication context checks. Organizations should follow ATT&CK technique T1566 which addresses phishing and social engineering attacks that often exploit CSRF vulnerabilities. The fix should align with OAuth2 security best practices and ensure that all callback endpoints properly validate the origin and integrity of authentication requests. Additionally, implementing proper logging and monitoring of authentication flows can help detect potential CSRF attack attempts and provide early warning of exploitation activities.