CVE-2007-2850 in MetaFrame
Summary
by MITRE
The Session Reliability Service (XTE) in Citrix MetaFrame Presentation Server 3.0, Presentation Server 4.0, and Access Essentials 1.0 and 1.5, allows remote attackers to bypass network security policies and connect to arbitrary TCP ports via a modified address:port string.
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Analysis
by VulDB Data Team • 09/03/2018
The vulnerability identified as CVE-2007-2850 resides within the Session Reliability Service (XTE) component of Citrix MetaFrame Presentation Server versions 3.0, 4.0, and Access Essentials 1.0 and 1.5. This flaw represents a critical security weakness that fundamentally undermines the network security architecture by allowing unauthorized access to internal systems. The vulnerability specifically affects the way the XTE service processes address and port information, creating a pathway for malicious actors to circumvent established network boundaries and gain access to systems that should remain protected behind firewalls or other network security controls. The impact extends beyond simple network access, as this vulnerability enables attackers to potentially reach sensitive internal services that are not directly exposed to external networks.
The technical mechanism behind this vulnerability involves the improper validation of address:port string inputs within the Session Reliability Service implementation. When the XTE service receives connection requests, it processes network addresses and port specifications without adequate sanitization or validation checks. This allows attackers to craft modified address:port strings that bypass normal network security policies and direct connections to arbitrary TCP ports within the internal network. The flaw essentially creates a backdoor mechanism within the legitimate service functionality, where the normal security boundaries that protect internal systems are effectively neutralized. This vulnerability operates at the network protocol level and specifically targets the session management and connection reliability features that are designed to maintain stable connections between clients and servers.
From an operational perspective, this vulnerability presents a severe risk to enterprise environments that rely on Citrix Presentation Server solutions for remote access and application delivery. Attackers exploiting this vulnerability can potentially gain access to internal network resources including databases, file servers, and other critical infrastructure components that are typically protected by network segmentation and firewall rules. The impact extends to potential data breaches, system compromise, and unauthorized access to sensitive corporate information. Organizations using these vulnerable versions of Citrix products face significant exposure, as the vulnerability allows for lateral movement within networks and can be leveraged as a stepping stone for more extensive attacks. The risk is particularly elevated in environments where network security policies are strictly enforced but the XTE service remains active and accessible.
The mitigation strategies for CVE-2007-2850 should focus on immediate remediation through official Citrix patches and updates, as this vulnerability was addressed through vendor security releases. Network administrators should implement additional protective measures including firewall rules that restrict access to the XTE service ports, disable the Session Reliability Service when not required, and conduct thorough network segmentation to limit potential attack vectors. The vulnerability aligns with CWE-20, which describes "Improper Input Validation," and represents a classic example of how insufficient validation can lead to privilege escalation and unauthorized access. From an ATT&CK framework perspective, this vulnerability maps to techniques involving network service exploitation and lateral movement, specifically targeting the execution and persistence phases of an attack lifecycle. Organizations should also implement network monitoring to detect anomalous connection patterns and ensure that all Citrix installations are updated to versions that properly address this vulnerability.