CVE-2017-9421 in Kiteworks
Summary
by MITRE
Authentication Bypass vulnerability in Accellion kiteworks before 2017.01.00 allows remote attackers to execute certain API calls on behalf of a web user using a gathered token via a POST request to /oauth/token.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 02/08/2020
The CVE-2017-9421 vulnerability represents a critical authentication bypass flaw in Accellion kiteworks software prior to version 2017.01.00. This vulnerability allows remote attackers to impersonate legitimate web users by exploiting a weakness in the token-based authentication mechanism. The flaw specifically manifests when an attacker can gather a valid token through unauthorized means and subsequently use it to execute privileged API calls against the system. The vulnerability occurs at the OAuth token endpoint where the system fails to properly validate the authenticity of the token before granting access to protected resources. This authentication bypass enables attackers to perform actions that should only be available to authorized users, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it allows attackers to operate within the system using legitimate user credentials without requiring knowledge of actual user passwords.
The technical implementation of this vulnerability stems from inadequate token validation mechanisms within the OAuth authentication flow. When a POST request is made to the /oauth/token endpoint, the system should verify the token's legitimacy and ensure it was issued to the requesting party. However, the vulnerable version of kiteworks fails to perform proper cryptographic validation of the token, allowing attackers to reuse tokens obtained through various means such as network sniffing, session hijacking, or previous successful authentication attempts. This flaw creates a pathway for attackers to escalate privileges and gain unauthorized access to sensitive functionality within the application. The vulnerability is classified under CWE-287 which addresses improper authentication issues, specifically focusing on the lack of proper validation of authentication tokens.
The operational impact of this vulnerability extends far beyond simple unauthorized access. Attackers who successfully exploit this flaw can execute arbitrary API calls on behalf of authenticated users, potentially leading to data exfiltration, privilege escalation, and complete system compromise. The vulnerability affects the integrity and confidentiality of the entire kiteworks platform, as it allows attackers to manipulate user sessions and access protected resources without proper authorization. Organizations using vulnerable versions of Accellion kiteworks face significant risk of data breaches, as attackers can leverage this vulnerability to gain access to sensitive information stored within the system. The remote nature of the attack means that adversaries can exploit this vulnerability from anywhere on the internet without requiring physical access to the target network, making it particularly attractive to threat actors.
Organizations should immediately upgrade to kiteworks version 2017.01.00 or later to address this vulnerability, as this release includes proper token validation mechanisms and authentication checks. Network administrators should implement monitoring solutions to detect unusual API activity patterns that might indicate exploitation attempts. Additional mitigations include implementing strict access controls for the /oauth/token endpoint, deploying web application firewalls to filter malicious requests, and conducting thorough security audits of all authentication mechanisms. The vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and credential access, as attackers can leverage legitimate tokens to maintain persistent access to systems. Security teams should also consider implementing token rotation mechanisms and enhanced logging to detect unauthorized token usage patterns that could indicate exploitation of this vulnerability.