CVE-2021-34909
📋 TL;DR
CVE-2021-34909 is a use-after-free vulnerability in Bentley View's JT file parser that allows remote code execution when a user opens a malicious JT file or visits a malicious webpage. Attackers can exploit this to execute arbitrary code with the privileges of the current user. This affects users of Bentley View 10.15.0.75 who open untrusted JT files.
💻 Affected Systems
- Bentley View
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via remote code execution with user privileges, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Malware installation or data exfiltration when users open malicious JT files from untrusted sources.
If Mitigated
Limited impact if users only open trusted JT files and the application runs with minimal privileges.
🎯 Exploit Status
Exploitation requires user interaction but is straightforward once malicious file is opened. No authentication required to trigger the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to Bentley View version 10.16.02 or later
Vendor Advisory: https://www.bentley.com/en/common-vulnerability-exposure/BE-2021-0005
Restart Required: Yes
Instructions:
1. Download latest Bentley View from official Bentley website. 2. Run installer. 3. Restart system after installation completes.
🔧 Temporary Workarounds
Disable JT file association
windowsRemove JT file type association with Bentley View to prevent automatic opening
Control Panel > Default Programs > Associate a file type or protocol with a program > Select .jt > Change program > Choose another application
Application whitelisting
windowsRestrict execution of Bentley View to trusted directories only
🧯 If You Can't Patch
- Implement strict email filtering to block JT attachments
- Educate users to never open JT files from untrusted sources
- Run Bentley View with restricted user privileges
🔍 How to Verify
Check if Vulnerable:
Check Bentley View version in Help > About. If version is 10.15.0.75, system is vulnerable.Check Version:
In Bentley View: Help > AboutVerify Fix Applied:
Verify version is 10.16.02 or later in Help > About menu.📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes of Bentley View
- Unusual file access patterns to JT files
- Process creation from Bentley View with suspicious command lines
Network Indicators:
- Outbound connections from Bentley View process to unknown IPs
- JT file downloads from untrusted sources
SIEM Query:
Process:Name='Bentley View' AND (EventID=1000 OR ParentProcess='explorer.exe' AND CommandLine CONTAINS '.jt')