CVE-2021-21104
📋 TL;DR
CVE-2021-21104 is a memory corruption vulnerability in Adobe Illustrator that allows remote code execution when a user opens a malicious file. Attackers can execute arbitrary code with the privileges of the current user. This affects Adobe Illustrator version 25.2 and earlier on all supported operating systems.
💻 Affected Systems
- Adobe Illustrator
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via remote code execution, allowing attackers to install malware, steal data, or pivot to other systems.
Likely Case
Malware installation or data theft through crafted Illustrator files sent via email or downloaded from malicious websites.
If Mitigated
Limited impact if users only open trusted files from verified sources and Illustrator is sandboxed.
🎯 Exploit Status
Exploitation requires user to open malicious file. No authentication needed beyond file access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 25.2.1 and later
Vendor Advisory: https://helpx.adobe.com/security/products/illustrator/apsb21-24.html
Restart Required: Yes
Instructions:
1. Open Adobe Illustrator. 2. Go to Help > Updates. 3. Install available updates to version 25.2.1 or later. 4. Restart Illustrator after installation.
🔧 Temporary Workarounds
Disable Illustrator file associations
windowsPrevent automatic opening of .ai files by changing default file associations
Use application sandboxing
allRun Illustrator in sandboxed environment to limit potential damage
🧯 If You Can't Patch
- Implement strict email filtering to block suspicious Illustrator attachments
- Educate users to only open Illustrator files from trusted sources and verify file integrity
🔍 How to Verify
Check if Vulnerable:
Check Illustrator version: Open Illustrator > Help > About Illustrator. If version is 25.2 or earlier, system is vulnerable.Check Version:
On Windows: Check registry HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Illustrator\25.0\Installer\Version. On macOS: Check /Applications/Adobe Illustrator/Contents/Info.plist CFBundleShortVersionStringVerify Fix Applied:
Verify version is 25.2.1 or later in Help > About Illustrator.📡 Detection & Monitoring
Log Indicators:
- Illustrator crash logs with memory access violations
- Unexpected child processes spawned from Illustrator
Network Indicators:
- Outbound connections from Illustrator to unknown IPs post-file opening
SIEM Query:
process_name:"Illustrator.exe" AND (event_id:1000 OR event_id:1001) OR parent_process:"Illustrator.exe" AND process_creation