Citrix Workspace App for Windows Incorrect Access Control Vulnerability (CVE-2019-11634) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTCitrix Workspace App for Windows before version 1904
Unauthenticated remote attackers can exploit incorrect access control mechanisms to execute arbitrary code and gain full system privileges on the target host
Immediately upgrade affected client installations to version 1904 or later, and restrict network access for unpatched endpoints
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Citrix recommends upgrading Citrix Workspace App for Windows to version 1904 or later. For enterprise-wide deployment, administrators can use SCCM or Active Directory GPO. Below is a PowerShell command for silent installation:
# Download and silently install the latest Citrix Workspace App
Start-Process -FilePath 'CitrixWorkspaceApp.exe' -ArgumentList '/silent /includeSSON /rcu' -Wait -NoNewWindow2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, mitigate the risk by disabling client drive redirection and virtual channel features via registry modification:
# Disable Client Drive Redirection via Registry
New-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Citrix\ICA Client\Engine\Configuration\Advanced\Modules\ClientDrive' -Name 'ClientDriveRedirection' -PropertyType 'String' -Value 'Off' -Force3. Log Audit & IoC Verification Commands
Use the following PowerShell script to audit the installed version of Citrix Workspace App and identify vulnerable endpoints:
$citrixPath = Get-ItemProperty -Path 'HKLM:\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*' | Where-Object { $_.DisplayName -like '*Citrix Workspace*' }
if ($citrixPath) {
$version = $citrixPath.DisplayVersion
Write-Host 'Detected Citrix Workspace Version:' $version
# Check if version is older than 19.4.0 (1904)
if ([System.Version]$version -lt [System.Version]'19.4.0') {
Write-Error 'VULNERABLE: Please upgrade to version 1904 or higher immediately.'
} else {
Write-Host 'SECURE: Version is up to date.' -ForegroundColor Green
}
} else {
Write-Host 'Citrix Workspace App is not installed on this system.'
}Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2019-11634) exists due to incorrect access control (CWE-284) within Citrix Workspace App for Windows. The application fails to properly validate and restrict access to internal virtual channels and local resources during inter-process communication (IPC) or API execution, allowing unauthorized entities to bypass security boundaries.
2. Exploitation Mechanics & Attack Scenario
An attacker can craft malicious session requests or packets directed at the Citrix Workspace App client. Because the client application implicitly trusts these requests without rigorous origin or privilege verification, the attacker can hijack virtual channel sessions or access local system files. This can be leveraged to achieve remote code execution (RCE) on the victim's machine without requiring user interaction.
3. Infrastructure & Business Impact
With a CVSS score of 9.8 (Critical) and its inclusion in the CISA Known Exploited Vulnerabilities (KEV) catalog, this vulnerability poses an active threat to enterprise environments. Successful exploitation allows attackers to compromise endpoint devices, establish a foothold within the corporate network, exfiltrate sensitive data, or deploy ransomware.
Official Vendor Advisories & References
Citrix Workspace App before 1904 for Windows has Incorrect Access Control.
Frequently Asked SecOps Questions (CVE-2019-11634)
FAQQ1. How critical is CVE-2019-11634 and is it actively exploited in the wild?
CVE-2019-11634 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 8.1%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2019-11634?
Primary impacted vendors include citrix across workspace app. Scope summary: All versions of Citrix Workspace App for Windows prior to 1904
Q3. What temporary mitigations or workarounds exist for CVE-2019-11634 before patching?
[Mitigation] Immediately upgrade affected client installations to version 1904 or later, and restrict network access for unpatched endpoints Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2019-11634
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