CVE-2021-31511 – CVE-2021-31511 is a heap-based buffer overflow ... (How to Fix)

Q: What is the severity of CVE-2021-31511?

CVE-2021-31511 has a CVSS score of 7.8 (HIGH). CVE-2021-31511 is a heap-based buffer overflow vulnerability in OpenText Brava! Desktop's PDF parser that allows remote code execution. Attackers can exploit this by tricking users into opening malicious PDF files or visiting malicious web pages. This affects OpenText Brava! Desktop users running vulnerable versions.

📋 TL;DR

CVE-2021-31511 is a heap-based buffer overflow vulnerability in OpenText Brava! Desktop's PDF parser that allows remote code execution. Attackers can exploit this by tricking users into opening malicious PDF files or visiting malicious web pages. This affects OpenText Brava! Desktop users running vulnerable versions.

💻 Affected Systems

Products:

OpenText Brava! Desktop

Versions: Build 16.6.4.55 and potentially earlier versions

Operating Systems: Windows

Default Config Vulnerable: ⚠️ Yes

Notes: All installations of the affected version are vulnerable by default when processing PDF files.

📦 What is this software?

Brava\! Desktop by Opentext

View all CVEs affecting Brava\! Desktop →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full system compromise with attacker gaining the same privileges as the Brava! Desktop process, potentially leading to data theft, ransomware deployment, or lateral movement within the network.

🟠

Likely Case

Remote code execution in the context of the current user, allowing attackers to install malware, steal sensitive documents, or establish persistence on the system.

🟢

If Mitigated

Limited impact with proper application sandboxing and user privilege restrictions, potentially resulting in application crash rather than code execution.

🌐 Internet-Facing: MEDIUM - Exploitation requires user interaction (opening malicious file/website), but PDF files are commonly shared and opened.

🏢 Internal Only: HIGH - Internal users frequently share PDF documents, making social engineering attacks effective within organizations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires user interaction but no authentication. The vulnerability is in a widely used PDF parsing component.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Later versions after Build 16.6.4.55

Vendor Advisory: https://www.opentext.com/products/brava

Restart Required: Yes

Instructions:

1. Check current Brava! Desktop version. 2. Download and install the latest version from OpenText's official website. 3. Restart the application and system if required. 4. Verify the update was successful.

🔧 Temporary Workarounds

Disable PDF file association

windows

Prevent Brava! Desktop from automatically opening PDF files

Control Panel > Default Programs > Set Associations > Change .pdf to another application

Application control restrictions

windows

Use application whitelisting to restrict Brava! Desktop execution

Windows Defender Application Control or third-party application control solution

🧯 If You Can't Patch

Implement network segmentation to isolate Brava! Desktop systems from critical assets
Deploy endpoint detection and response (EDR) solutions to monitor for exploitation attempts

🔍 How to Verify

Check if Vulnerable:

Check Help > About in Brava! Desktop to see if version is Build 16.6.4.55 or earlier

Check Version:

Not applicable - check via application GUI Help > About menu

Verify Fix Applied:

Verify version is later than Build 16.6.4.55 and test with known safe PDF files

📡 Detection & Monitoring

Log Indicators:

Application crashes of Brava! Desktop
Unusual process creation from Brava! Desktop
Multiple failed PDF parsing attempts

Network Indicators:

Downloads of PDF files from untrusted sources
External connections initiated by Brava! Desktop process

SIEM Query:

Process Creation where Parent Process contains 'brava' AND (Command Line contains '.pdf' OR Image contains suspicious patterns)

📊 Metadata

CVE ID: CVE-2021-31511

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-787

Published: June 29, 2021

Last Updated: November 21, 2024

🔗 References

https://www.zerodayinitiative.com/advisories/ZDI-21-689/ Third Party Advisory,VDB Entry
https://www.cvedetails.com/vulnerability-list/vendor_id-2032/product_id-96672/Opentext-Brava-Desktop.html?page=1&opec=1&order=1&trc=35&sha=37f4ed0596f8ccacca7d571f22a38c97b0f19f4c Third Party Advisory
https://www.opentext.com/products/brava Product
https://www.zerodayinitiative.com/advisories/ZDI-21-689/ Third Party Advisory,VDB Entry

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🔗 Related Vulnerabilities

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