CVE-2006-6334 in Presentation Server
Summary
by MITRE
Heap-based buffer overflow in the SendChannelData function in wfica.ocx in Citrix Presentation Server Client before 9.230 for Windows allows remote malicious web sites to execute arbitrary code via a DataSize parameter that is less than the length of the Data buffer.
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Analysis
by VulDB Data Team • 06/15/2025
The vulnerability identified as CVE-2006-6334 represents a critical heap-based buffer overflow flaw within the Citrix Presentation Server Client component wfica.ocx version 9.229 and earlier. This vulnerability resides in the SendChannelData function, which processes data transmission operations within the Citrix client environment. The flaw manifests when malicious web sites attempt to exploit the DataSize parameter validation mechanism, creating a condition where the parameter value falls short of the actual Data buffer length, thereby enabling attackers to overwrite adjacent memory locations on the heap.
The technical exploitation of this vulnerability leverages the improper bounds checking within the SendChannelData function, which fails to validate that the DataSize parameter accurately reflects the actual data buffer dimensions. When a remote malicious web site crafts a specially crafted request with a DataSize value smaller than the Data buffer length, the function proceeds to copy data beyond the allocated heap memory boundaries. This heap corruption creates opportunities for arbitrary code execution, as attackers can manipulate memory contents to redirect program execution flow or inject malicious payloads.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a severe remote code execution threat that can be exploited through web browser interactions without requiring user interaction beyond visiting a malicious website. The vulnerability affects Citrix Presentation Server Client versions prior to 9.230, making it particularly dangerous for organizations that have not implemented proper patch management protocols. Attackers exploiting this vulnerability can potentially gain full system control, escalate privileges, and access sensitive data within the compromised environment, especially in enterprise settings where Citrix clients are commonly deployed for remote access solutions.
Security practitioners should consider this vulnerability in the context of the CWE-121 heap-based buffer overflow classification, which specifically addresses buffer overflows occurring in heap memory regions. The attack vector aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation, as successful exploitation typically enables attackers to execute arbitrary commands and potentially escalate their privileges within the compromised system. Organizations should prioritize immediate patch deployment to Citrix Presentation Server Client versions 9.230 and later, while implementing network monitoring to detect potential exploitation attempts and establishing robust patch management processes to prevent similar vulnerabilities from being exploited in the future.
The vulnerability demonstrates the critical importance of proper input validation and memory management practices in client-side applications, particularly those handling remote data transmission operations. This flaw underscores the necessity of comprehensive security testing including fuzzing and memory corruption analysis, as well as the implementation of modern exploit mitigation techniques such as address space layout randomization and data execution prevention. Organizations utilizing Citrix client solutions should conduct thorough security assessments of their remote access infrastructure and ensure that all client components remain up-to-date with the latest security patches to prevent exploitation of similar vulnerabilities in the future.