CVE-2021-1526
📋 TL;DR
CVE-2021-1526 is a remote code execution vulnerability in Cisco Webex Player for Windows and macOS. Attackers can exploit it by tricking users into opening malicious Webex Recording Format (WRF) files, allowing arbitrary code execution with the user's privileges. This affects all users of vulnerable Webex Player versions.
💻 Affected Systems
- Cisco Webex Player
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining the same privileges as the targeted user, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Malware installation or credential theft through social engineering attacks where users open malicious WRF files received via email or links.
If Mitigated
Limited impact if users avoid opening untrusted WRF files and systems are properly segmented with application whitelisting.
🎯 Exploit Status
Exploitation requires user interaction to open malicious WRF files. No authentication is needed as the vulnerability is in file parsing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Webex Player 41.5 and later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-player-kOf8zVT
Restart Required: Yes
Instructions:
1. Download Webex Player 41.5 or later from Cisco's official site. 2. Install the update following standard installation procedures. 3. Restart the system to ensure the update is fully applied.
🔧 Temporary Workarounds
Disable WRF file association
allRemove the file association for .wrf files to prevent automatic opening with Webex Player
Windows: Use 'Default Programs' in Control Panel to change .wrf file association
macOS: Right-click .wrf file > Get Info > Open With > Change to different application
Application control/whitelisting
allUse application control solutions to block execution of Webex Player or restrict to trusted locations
Windows: Use AppLocker or Windows Defender Application Control policies
macOS: Use Gatekeeper or third-party application control solutions
🧯 If You Can't Patch
- Implement strict email filtering to block .wrf attachments
- Educate users to never open .wrf files from untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check Webex Player version: Windows - Open Webex Player > Help > About; macOS - Open Webex Player > Webex Player menu > About Webex PlayerCheck Version:
Windows: wmic product where name='Webex Player' get version; macOS: /Applications/Webex\ Player.app/Contents/Info.plist | grep -A1 CFBundleShortVersionStringVerify Fix Applied:
Verify version is 41.5 or higher using the same method as checking vulnerability📡 Detection & Monitoring
Log Indicators:
- Process creation events for Webex Player with suspicious parent processes
- File creation events for .wrf files from email clients or downloads
Network Indicators:
- Downloads of .wrf files from untrusted sources
- Email attachments with .wrf extension
SIEM Query:
source="*" (file_extension=".wrf" OR process_name="Webex Player") AND (parent_process="outlook.exe" OR parent_process="chrome.exe" OR parent_process="firefox.exe")