CVE-2017-1000070 in oauth2_proxy
Summary
by MITRE
The Bitly oauth2_proxy in version 2.1 and earlier was affected by an open redirect vulnerability during the start and termination of the 2-legged OAuth flow. This issue was caused by improper input validation and a violation of RFC-6819
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Analysis
by VulDB Data Team • 12/12/2022
The vulnerability identified as CVE-2017-1000070 affects the Bitly oauth2_proxy component in versions 2.1 and earlier, representing a critical open redirect flaw that undermines the security of the 2-legged OAuth authentication process. This vulnerability specifically manifests during the initiation and conclusion of the OAuth flow, creating a pathway for attackers to exploit the authentication mechanism. The flaw stems from inadequate input validation practices that fail to properly sanitize or verify redirect URLs provided during the OAuth handshake process, allowing malicious actors to manipulate the flow and redirect users to arbitrary destinations.
The technical implementation of this vulnerability violates established security standards including RFC-6819, which provides comprehensive guidelines for securing OAuth 2.0 implementations and specifically addresses the risks associated with open redirects in OAuth flows. This RFC outlines the importance of validating redirect URIs against a pre-registered list of trusted endpoints to prevent attackers from crafting malicious redirect URLs that could lead to phishing attacks or credential theft. The violation of these established protocols creates a significant security gap where the oauth2_proxy fails to enforce proper redirect URI validation, making it susceptible to manipulation by threat actors who can craft malicious URLs to redirect users to attacker-controlled domains.
The operational impact of this vulnerability extends beyond simple redirect manipulation, as it can enable sophisticated phishing attacks where users are deceived into believing they are authenticating with legitimate services while actually being redirected to malicious sites. Attackers can exploit this flaw to capture authentication tokens, credentials, or other sensitive information transmitted during the OAuth process. The vulnerability affects the integrity of the entire authentication flow by undermining the trust model that OAuth 2.0 is designed to establish, potentially allowing unauthorized access to protected resources and compromising user accounts. This risk is particularly severe in environments where the oauth2_proxy is used to secure access to enterprise applications or sensitive data repositories.
Security mitigations for this vulnerability require immediate implementation of proper input validation mechanisms that enforce strict validation of redirect URIs against a predefined whitelist of trusted endpoints. Organizations should implement comprehensive URL validation that ensures all redirect destinations are explicitly authorized and registered within the application configuration. The fix involves updating the oauth2_proxy component to version 2.2 or later where the vulnerability has been addressed through proper input sanitization and adherence to OAuth 2.0 security best practices. Additionally, security teams should conduct thorough penetration testing to identify any other potential redirect vulnerabilities within their OAuth implementations and ensure compliance with industry standards such as those defined in the CWE catalog under category CWE-601 for URL Redirects. The remediation process should also include implementing proper logging and monitoring of redirect activities to detect anomalous behavior that might indicate exploitation attempts.