CVE-2021-42721
📋 TL;DR
CVE-2021-42721 is a use-after-free vulnerability in Adobe Bridge versions 11.1.1 and earlier that allows arbitrary code execution when processing malicious files. Attackers can exploit this by tricking users into opening specially crafted files, potentially gaining control of the affected system. This affects all users running vulnerable versions of Adobe Bridge.
💻 Affected Systems
- Adobe Bridge
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining the same privileges as the current user, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Malicious code execution leading to credential theft, data exfiltration, or installation of additional malware payloads.
If Mitigated
Limited impact with proper application sandboxing and user privilege restrictions, potentially preventing system-wide compromise.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious file) and knowledge of memory corruption techniques. No public exploits were available at disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Bridge 11.1.2 and later
Vendor Advisory: https://helpx.adobe.com/security/products/bridge/apsb21-94.html
Restart Required: Yes
Instructions:
1. Open Adobe Bridge. 2. Go to Help > Check for Updates. 3. Follow prompts to install Bridge 11.1.2 or later. 4. Restart Bridge after installation completes.
🔧 Temporary Workarounds
Disable automatic file processing
allPrevent Bridge from automatically processing potentially malicious files by adjusting security settings.
Restrict file types
allConfigure system or application to block suspicious file types from being opened in Bridge.
🧯 If You Can't Patch
- Run Bridge with minimal user privileges to limit potential damage from exploitation
- Implement application whitelisting to prevent execution of unauthorized code
🔍 How to Verify
Check if Vulnerable:
Open Adobe Bridge, go to Help > About Adobe Bridge, check if version is 11.1.1 or earlier.Check Version:
On Windows: Check registry at HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Bridge\Version. On macOS: Check /Applications/Adobe Bridge/Contents/Info.plist for CFBundleShortVersionString.Verify Fix Applied:
After updating, verify version is 11.1.2 or later in Help > About Adobe Bridge.📡 Detection & Monitoring
Log Indicators:
- Unexpected Bridge crashes
- Suspicious file access patterns in Bridge logs
- Unusual child process creation from Bridge
Network Indicators:
- Unexpected outbound connections from Bridge process
- DNS requests to suspicious domains after file opening
SIEM Query:
process_name:"bridge.exe" AND (event_type:crash OR child_process_name:suspicious.exe)