CVE-2001-1192 in ICA Client
Summary
by MITRE
Citrix Independent Computing Architecture (ICA) Client for Windows 6.1 allows remote malicious web sites to execute arbitrary code via a .ICA file, which is downloaded and automatically executed by the client.
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Analysis
by VulDB Data Team • 04/10/2019
The vulnerability described in CVE-2001-1192 represents a critical security flaw in the Citrix Independent Computing Architecture ICA Client for Windows version 6.1. This vulnerability stems from the client's improper handling of .ICA files, which are configuration files used to establish remote desktop connections to Citrix servers. The flaw allows malicious web sites to craft specially designed .ICA files that, when downloaded and automatically executed by the vulnerable client, can trigger arbitrary code execution on the target system. This represents a classic example of a remote code execution vulnerability that can be exploited through web-based attacks without requiring any user interaction beyond visiting a malicious website.
The technical implementation of this vulnerability involves the ICA client's automatic execution mechanism for .ICA files downloaded from web sources. When a user visits a malicious website that hosts a specially crafted .ICA file, the client automatically processes and executes this file without proper validation or user confirmation. The flaw lies in the client's trust model, which assumes that any .ICA file downloaded from a web source is legitimate and safe to execute. This design decision creates an attack surface where remote adversaries can leverage web delivery mechanisms to bypass traditional security controls and directly compromise the client system. The vulnerability is classified under CWE-94, which describes "External Control of Code Generation" where an attacker can influence the generation of executable code through external inputs.
The operational impact of this vulnerability is severe and far-reaching for organizations relying on Citrix ICA clients for remote access. Attackers can leverage this vulnerability to gain complete control over affected systems, potentially leading to data breaches, lateral movement within networks, and establishment of persistent backdoors. The automatic execution behavior means that users do not need to perform any specific actions to be compromised, making this attack vector particularly dangerous and difficult to defend against through user education alone. Organizations with remote workers or distributed access requirements using Citrix ICA clients face significant risk exposure, as a single compromised web page can lead to widespread system compromise across an enterprise network.
Mitigation strategies for CVE-2001-1192 should focus on immediate patching of the vulnerable ICA client software, as Citrix released security updates to address this specific vulnerability. Organizations should also implement network-level controls to prevent automatic execution of .ICA files from untrusted sources and consider disabling automatic download and execution features in the client configuration. The implementation of web application firewalls and content filtering solutions can help block malicious .ICA file delivery attempts. Additionally, security awareness training should emphasize the dangers of visiting untrusted websites and the importance of verifying the legitimacy of downloaded files. This vulnerability aligns with ATT&CK technique T1193, which describes "Spearphishing via Service" and represents a common exploitation pattern where attackers use web-based delivery mechanisms to execute malicious code on target systems, making it a critical concern for enterprise security teams implementing remote access solutions.