CVE-2021-34927
📋 TL;DR
CVE-2021-34927 is a buffer overflow vulnerability in Bentley View's JT file parser that allows remote code execution. Attackers can exploit this by tricking users into opening malicious JT files, potentially compromising their systems. This affects users of Bentley View version 10.15.0.75.
💻 Affected Systems
- Bentley View
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the victim's computer, data theft, and lateral movement within the network.
Likely Case
Local privilege escalation leading to malware installation, data exfiltration, and persistence mechanisms being established on the compromised system.
If Mitigated
Limited impact due to sandboxing or application hardening, potentially resulting in application crash rather than code execution.
🎯 Exploit Status
Exploitation requires user interaction but is technically straightforward once malicious JT file is crafted.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.16.0.80 or later
Vendor Advisory: https://www.bentley.com/en/common-vulnerability-exposure/BE-2021-0005
Restart Required: Yes
Instructions:
1. Download latest Bentley View installer from Bentley website. 2. Run installer as administrator. 3. Follow installation prompts. 4. Restart computer 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 different application
Block JT files at perimeter
allConfigure email/web gateways to block JT file attachments and downloads
🧯 If You Can't Patch
- Implement application allowlisting to prevent unauthorized applications from executing
- Deploy endpoint detection and response (EDR) solutions to monitor for suspicious file parsing behavior
🔍 How to Verify
Check if Vulnerable:
Check Bentley View version in Help > About. If version is exactly 10.15.0.75, system is vulnerable.Check Version:
wmic product where name="Bentley View" get versionVerify Fix Applied:
Verify version is 10.16.0.80 or higher in Help > About menu.📡 Detection & Monitoring
Log Indicators:
- Application crashes in Bentley View with JT file parsing errors
- Unusual process creation from Bentley View executable
Network Indicators:
- Downloads of JT files from untrusted sources
- Outbound connections from Bentley View to suspicious IPs
SIEM Query:
source="windows" AND (process_name="BentleyView.exe" AND (event_id=1000 OR event_id=1001)) OR (file_extension=".jt" AND download_source="external")