CVE-2006-3549 in Application Framework
Summary
by MITRE
services/go.php in Horde Application Framework 3.0.0 through 3.0.10 and 3.1.0 through 3.1.1 does not properly restrict its image proxy capability, which allows remote attackers to perform "Web tunneling" attacks and use the server as a proxy via (1) http, (2) https, and (3) ftp URL in the url parameter, which is requested from the server.
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Analysis
by VulDB Data Team • 06/22/2019
The vulnerability described in CVE-2006-3549 represents a critical security flaw in the Horde Application Framework that enables remote attackers to exploit the image proxy functionality for unauthorized network access. This issue affects versions 3.0.0 through 3.0.10 and 3.1.0 through 3.1.1, making it a widespread concern across multiple release branches of the framework. The flaw resides in the services/go.php component where the application fails to properly validate and restrict incoming URL parameters, creating a pathway for malicious actors to leverage the server as an intermediary for network communications.
The technical implementation of this vulnerability stems from inadequate input validation within the image proxy mechanism. When users provide URLs through the url parameter, the system does not sufficiently sanitize or restrict the protocols that can be processed, allowing attackers to specify http, https, and ftp protocols directly within the proxy functionality. This oversight creates an environment where the server becomes an unwitting participant in network tunneling operations, enabling attackers to route their traffic through the compromised system. The vulnerability specifically manifests when the application processes external URLs for image display purposes, but due to insufficient protocol validation, it accepts and processes requests for various network protocols beyond simple image retrieval.
From an operational perspective, this vulnerability presents significant risks to organizations deploying affected versions of the Horde Application Framework. Attackers can utilize the compromised proxy functionality to bypass network security controls, access internal resources that would otherwise be restricted, and potentially conduct reconnaissance activities without detection. The web tunneling capabilities enabled by this flaw allow malicious actors to use the server as a pivot point for further attacks, making it particularly dangerous in environments where the framework serves as a gateway or intermediary system. The impact extends beyond simple data exfiltration, as the proxy functionality can be used to establish persistent connections and maintain access to target networks through the compromised server.
The vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic case of insecure direct object reference that has been extended to enable proxy-based attacks. From an adversarial perspective, this flaw maps directly to ATT&CK technique T1090, which covers proxy usage for network penetration and evasion activities. Organizations should implement immediate mitigations including patching to the latest available versions of the Horde Framework, implementing strict URL validation for proxy functionality, and deploying network monitoring to detect anomalous proxy usage patterns. Additional defensive measures should include restricting the proxy capabilities to only trusted domains, implementing rate limiting for proxy requests, and configuring firewalls to block unauthorized proxy protocols. The remediation process should also involve comprehensive security testing to ensure no other similar vulnerabilities exist within the application's proxy mechanisms, as this type of flaw often indicates broader input validation issues that require systematic review and hardening of the application's security posture.