CVE-2021-41832
📋 TL;DR
CVE-2021-41832 is a signature validation bypass vulnerability in Apache OpenOffice that allows attackers to manipulate documents to appear as if they were signed by a trusted source. This affects all versions up to 4.1.10, potentially tricking users into opening malicious documents. Users who open untrusted OpenOffice documents are at risk.
💻 Affected Systems
- Apache OpenOffice
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could distribute malicious documents appearing to be from trusted sources, leading to malware installation, data theft, or system compromise when users open them.
Likely Case
Users could be tricked into opening phishing documents or malware-laden files that appear legitimate due to forged signatures.
If Mitigated
With proper security awareness training and document validation processes, users would avoid opening suspicious documents even with forged signatures.
🎯 Exploit Status
Exploitation requires the attacker to create a specially crafted document and convince the user to open it. No authentication is required once the document is opened.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.1.11
Vendor Advisory: https://lists.apache.org/thread.html/rfbc93cd7cea40e2ad3b6e080f688dd02566cdd2b1984fcbb6f8b0fb6@<announce.apache.org>
Restart Required: No
Instructions:
1. Download Apache OpenOffice 4.1.11 or later from the official website. 2. Uninstall the current version. 3. Install the updated version. 4. Verify the installation by checking the version number.
🔧 Temporary Workarounds
Use LibreOffice Instead
allSwitch to LibreOffice which has addressed similar issues (see CVE-2021-25635) and is actively maintained.
Disable Document Macros
allConfigure OpenOffice to disable macros and scripting in documents to reduce attack surface.
🧯 If You Can't Patch
- Implement strict policies to only open documents from verified, trusted sources.
- Use application whitelisting to restrict execution of untrusted OpenOffice documents.
🔍 How to Verify
Check if Vulnerable:
Check the OpenOffice version via Help > About Apache OpenOffice. If version is 4.1.10 or earlier, the system is vulnerable.Check Version:
On Linux: soffice --version | head -1Verify Fix Applied:
After updating, verify the version shows 4.1.11 or later in Help > About Apache OpenOffice.📡 Detection & Monitoring
Log Indicators:
- Unusual document opening patterns from untrusted sources
- Security software alerts about document signature validation failures
Network Indicators:
- Downloads of OpenOffice documents from suspicious sources
- Network traffic patterns associated with document-based attacks
SIEM Query:
source="openoffice" AND event="document_open" AND signature_status="invalid"🔗 References
- https://lists.apache.org/thread.html/rd3214a568b43dd335b5d558f521377f4bff750684dea18eb041fc1bb%40%3Cusers.openoffice.apache.org%3E
- https://lists.apache.org/thread.html/rfbc93cd7cea40e2ad3b6e080f688dd02566cdd2b1984fcbb6f8b0fb6%40%3Cannounce.apache.org%3E
- https://lists.apache.org/thread.html/rd3214a568b43dd335b5d558f521377f4bff750684dea18eb041fc1bb%40%3Cusers.openoffice.apache.org%3E
- https://lists.apache.org/thread.html/rfbc93cd7cea40e2ad3b6e080f688dd02566cdd2b1984fcbb6f8b0fb6%40%3Cannounce.apache.org%3E
