CVE-2024-6148: Citrix Workspace Auth Bypass Vulnerability

CVE-2024-6148 Overview

CVE-2024-6148 is an authorization bypass vulnerability affecting Citrix Workspace app for HTML5 that allows authenticated attackers to bypass Global App Configuration Service (GACS) policy configuration settings. This security flaw enables users with low-level privileges to circumvent security controls that administrators have configured to enforce organizational policies, potentially leading to unauthorized access to features or data that should be restricted.

Critical Impact

Authenticated users can bypass GACS policy restrictions in Citrix Workspace app for HTML5, undermining administrative security controls and potentially exposing sensitive resources or enabling unauthorized actions within the virtualized workspace environment.

Affected Products

• Citrix Workspace app for HTML5 (all versions prior to patched release)
• Citrix Workspace (HTML5 client)

Discovery Timeline

• 2024-07-10 - CVE-2024-6148 published to NVD
• 2025-03-25 - Last updated in NVD database

Technical Details for CVE-2024-6148

Vulnerability Analysis

This vulnerability stems from improper access control mechanisms within the Citrix Workspace app for HTML5, specifically related to the Global App Configuration Service (GACS) policy enforcement. GACS is designed to allow administrators to centrally manage and enforce configuration settings across Citrix Workspace deployments. When functioning correctly, these policies should restrict user capabilities based on organizational security requirements.

The flaw allows authenticated users to bypass these configured policy restrictions. This means security settings intended to control user behavior—such as clipboard access, file transfer permissions, session recording policies, or other workspace restrictions—can be circumvented by users who should otherwise be bound by these controls.

The vulnerability is classified under CWE-276 (Incorrect Default Permissions), indicating that the underlying issue relates to improper permission enforcement within the application's policy handling mechanism.

Root Cause

The root cause of CVE-2024-6148 lies in the incorrect handling of permission enforcement within the GACS policy configuration subsystem. The Citrix Workspace app for HTML5 fails to properly validate and enforce policy restrictions at the client side, allowing authenticated users to manipulate or bypass policy settings that should be enforced by the server-side configuration. This improper access control implementation enables users to access functionality or resources that administrators intended to restrict through GACS policies.

Attack Vector

The attack vector for this vulnerability is network-based and requires authentication. An attacker must first have valid credentials to access the Citrix Workspace environment. Once authenticated, the attacker can exploit the policy bypass vulnerability to circumvent administrative restrictions. The attack does not require user interaction beyond the initial authentication, and the complexity is low, making it accessible to attackers with basic technical knowledge.

The exploitation process involves manipulating the client-side policy enforcement mechanisms within the HTML5 Workspace app to bypass GACS restrictions. This could allow unauthorized access to features such as local drive mapping, clipboard functionality, printing capabilities, or other workspace features that administrators intended to disable.

Detection Methods for CVE-2024-6148

Indicators of Compromise

• Unexpected user access to features that should be disabled by GACS policies (clipboard, file transfer, printing)
• Discrepancies between configured GACS policies and actual user session capabilities
• Unusual client-side behavior in Citrix Workspace HTML5 sessions that circumvents expected restrictions
• Authentication logs showing users accessing restricted resources or features

Detection Strategies

• Monitor Citrix Director and analytics for policy compliance violations
• Implement session recording and review for sensitive user accounts to detect policy bypass attempts
• Deploy endpoint detection solutions to identify anomalous Citrix Workspace client behavior
• Audit GACS policy configurations against actual enforced settings in user sessions

Monitoring Recommendations

• Enable detailed logging for Citrix Workspace app for HTML5 sessions
• Configure alerts for policy violation events in Citrix Cloud or on-premises Citrix infrastructure
• Regularly audit user session capabilities against configured GACS policies
• Monitor network traffic for unusual data transfer patterns from Workspace sessions

How to Mitigate CVE-2024-6148

Immediate Actions Required

• Apply the security patch from Citrix immediately as referenced in Citrix Support Article CTX678037
• Review and audit current GACS policy configurations to understand potential exposure
• Monitor user sessions for any suspicious activity or policy bypass indicators
• Consider temporarily restricting access to sensitive resources until patching is complete

Patch Information

Citrix has released a security update to address this vulnerability. Administrators should consult the Citrix Support Article CTX678037 for detailed patch information, affected version specifics, and upgrade instructions. The patch addresses the improper permission enforcement in the GACS policy configuration handling mechanism.

Organizations using Citrix Workspace app for HTML5 should prioritize applying this update, particularly in environments where GACS policies are used to enforce security-critical restrictions.

Workarounds

• Implement additional server-side access controls to supplement client-side GACS policies
• Consider using Citrix Workspace app for Windows or other native clients where more robust policy enforcement may be available
• Restrict access to sensitive applications and resources at the network or application level until patching can be completed
• Enable enhanced session monitoring and logging to detect potential exploitation attempts