CVE-2019-7218 in ShareFile
Summary
by MITRE
Citrix ShareFile through 19.1 allows a downgrade from two-factor authentication to one-factor authentication. An attacker with access to the offline victim?s otp physical token or virtual app (like google authenticator) is able to bypass the first authentication phase (username/password mechanism) and log-in using username/otp combination only (phase 2 of 2FA).
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Analysis
by VulDB Data Team • 09/17/2023
The vulnerability identified as CVE-2019-7218 affects Citrix ShareFile versions through 19.1 and represents a significant security flaw in the two-factor authentication implementation. This weakness allows attackers to manipulate the authentication process and effectively downgrade security from a robust two-factor approach to a less secure single-factor mechanism. The vulnerability specifically targets the authentication flow where users are expected to provide both a username/password combination and a time-based one-time password from a physical token or mobile application such as Google Authenticator.
The technical flaw lies in the improper handling of authentication state transitions within the Citrix ShareFile system. When a user attempts to authenticate, the system should maintain the requirement for both authentication factors throughout the entire process. However, this vulnerability enables an attacker who has compromised access to the victim's OTP token to exploit a flaw in the authentication session management. The attacker can bypass the initial username and password phase and proceed directly to the second phase using only the username and OTP combination, effectively rendering the first authentication factor obsolete.
This security weakness creates substantial operational impact for organizations using Citrix ShareFile as their file sharing solution. The vulnerability undermines the fundamental security principle of defense in depth by allowing attackers to weaken the authentication requirements after initial access has been gained. Organizations may experience unauthorized access to sensitive files and data, potentially leading to data breaches, intellectual property theft, and compliance violations. The attack vector is particularly concerning because it requires only access to the victim's OTP token, which may be obtained through physical theft, social engineering, or other means of compromise.
The vulnerability aligns with CWE-312 (Sensitive Data Exposure) and CWE-313 (Cryptographic Issues) categories, as it exposes authentication mechanisms to manipulation and potentially compromises the integrity of the authentication process. From an ATT&CK framework perspective, this vulnerability maps to T1110 (Brute Force) and T1078 (Valid Accounts) techniques, as attackers can leverage compromised tokens to authenticate without proper credentials. Organizations should implement immediate mitigations including updating to patched versions of Citrix ShareFile, reviewing authentication policies, and strengthening monitoring for suspicious authentication patterns. Additional controls such as account lockout mechanisms, multi-factor authentication enforcement, and regular security audits should be implemented to reduce the risk of exploitation. The vulnerability also highlights the importance of proper session management and authentication state validation in enterprise applications to prevent such downgrade attacks.