CVE-2011-1409 in fex
Summary
by MITRE
Frams s Fast File EXchange (F*EX, aka fex) 20100208, and possibly other versions before 20110610, allows remote attackers to bypass authentication and upload arbitrary files via a request that lacks an authentication ID.
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability identified as CVE-2011-1409 affects Frams Fast File EXchange (F*EX) versions up to and including 20100208, with potential impacts extending to other versions prior to the 20110610 release. This authentication bypass flaw represents a critical security weakness that fundamentally undermines the file transfer system's access control mechanisms. The vulnerability manifests when the application fails to properly validate authentication credentials during file upload operations, creating an exploitable condition that allows unauthorized users to bypass the intended security controls.
The technical flaw resides in the application's authentication handling logic where the system does not adequately verify the presence or validity of authentication identifiers in incoming requests. When a client attempts to upload files through the F*EX interface, the system should require a valid authentication ID to be present in the request headers or parameters. However, the vulnerable implementation accepts upload requests even when this authentication token is completely absent from the communication, effectively allowing any remote attacker to submit files without proper authorization. This represents a classic failure in input validation and access control enforcement that aligns with CWE-287, which addresses improper handling of authentication tokens.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, as it enables remote attackers to execute arbitrary file uploads on vulnerable systems. Attackers can leverage this flaw to deploy malicious payloads, including web shells, malware, or other harmful content that can compromise the entire file exchange infrastructure. The implications are particularly severe in environments where F*EX serves as a file transfer mechanism for sensitive data, as unauthorized uploads can lead to data breaches, system compromise, and potential lateral movement within network environments. This vulnerability directly enables the attack pattern described in the MITRE ATT&CK framework under T1195.001 for 'Supply Chain Compromise' and T1078.004 for 'Valid Accounts' when attackers can leverage the bypassed authentication to establish persistent access.
The security implications of this vulnerability are compounded by the fact that it operates at the application layer without requiring any special privileges or advanced exploitation techniques. Remote attackers can simply craft HTTP requests that omit the authentication ID parameter and successfully submit files to the system, making the attack surface extremely broad and accessible. Organizations relying on F*EX for file transfer operations face significant risks including data exfiltration, system infiltration, and potential regulatory compliance violations. The vulnerability's persistence across multiple versions also suggests a systemic issue in the application's security architecture that requires comprehensive review and remediation.
Mitigation strategies should focus on immediate patching of affected versions to the secure 20110610 release or later, which addresses the authentication bypass flaw through proper validation of authentication tokens. Additionally, organizations should implement network-level controls such as firewall rules to restrict access to F*EX services, enforce strong authentication mechanisms, and monitor for unauthorized file upload activities. The implementation of request validation controls, including mandatory authentication header checks, should be enforced at the application level to prevent similar vulnerabilities from occurring in other components. Regular security assessments and input validation reviews should be conducted to identify and remediate similar authentication bypass conditions that may exist in other parts of the system infrastructure.