CVE-2016-1000001 in Flask-oidc
Summary
by MITRE
flask-oidc version 0.1.2 and earlier is vulnerable to an open redirect
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Analysis
by VulDB Data Team • 07/23/2019
The vulnerability identified as CVE-2016-1000001 affects flask-oidc version 0.1.2 and earlier, representing a critical open redirect flaw that can be exploited by malicious actors to manipulate user navigation and potentially execute phishing attacks. This vulnerability specifically impacts applications that utilize the OpenID Connect authentication framework within Flask web applications, creating a significant security risk for organizations relying on this authentication module. The flaw exists in the redirect handling mechanism of the flask-oidc library, which fails to properly validate redirect URLs before directing users to external domains.
The technical implementation of this vulnerability stems from insufficient input validation within the OpenID Connect redirect processing logic. When users attempt to authenticate through the flask-oidc module, the application accepts redirect URLs without proper sanitization or domain verification. This allows attackers to craft malicious redirect URLs that point to phishing sites or malicious domains, effectively bypassing the intended security controls of the authentication flow. The vulnerability operates at the application layer and can be exploited through manipulation of the redirect_uri parameter in OpenID Connect authentication requests. According to CWE standards, this maps to CWE-601 Open Redirect vulnerability, which is classified as a medium to high severity issue due to its potential for user deception and credential theft.
The operational impact of this vulnerability extends beyond simple redirect manipulation, as it can enable sophisticated social engineering attacks and credential harvesting operations. Attackers can exploit this flaw to redirect authenticated users to malicious domains that mimic legitimate authentication portals, potentially capturing user credentials or other sensitive information. The vulnerability affects the integrity of the authentication process and can compromise user sessions, particularly in environments where users trust the legitimate application domain. Organizations using flask-oidc versions prior to 0.1.3 are at risk of having their users redirected to attacker-controlled domains, undermining the security assurances provided by the OpenID Connect protocol.
Mitigation strategies for this vulnerability require immediate action to upgrade the flask-oidc library to version 0.1.3 or later, which includes proper redirect URL validation and sanitization. System administrators should implement comprehensive monitoring of authentication flows to detect unusual redirect patterns and establish strict domain whitelisting policies for redirect destinations. Additionally, organizations should consider implementing additional security controls such as HTTP Strict Transport Security headers and Content Security Policy directives to further protect against unauthorized redirects. The remediation process should include thorough testing of the updated library to ensure that legitimate redirect functionality remains intact while eliminating the security gap. According to ATT&CK framework, this vulnerability aligns with T1566 Phishing techniques and T1071.004 Application Layer Protocol: DNS, as attackers can leverage the redirect functionality to establish malicious domains for credential harvesting operations. Organizations should also conduct security audits of their authentication systems to identify any other potential redirect vulnerabilities and implement proper input validation across all authentication-related components.