CVE-2024-21411
📋 TL;DR
CVE-2024-21411 is a remote code execution vulnerability in Skype for Consumer that allows attackers to execute arbitrary code on affected systems. Attackers could exploit this vulnerability by sending specially crafted content to a Skype user. All users running vulnerable versions of Skype for Consumer are affected.
💻 Affected Systems
- Skype for Consumer
📦 What is this software?
Skype by Skype
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the victim's computer, enabling data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Attacker executes malicious code with user privileges, potentially leading to credential theft, surveillance, or lateral movement within the network.
If Mitigated
With proper patching and network segmentation, impact is limited to isolated systems with minimal data exposure.
🎯 Exploit Status
Exploitation requires user interaction such as clicking a link or opening malicious content. No public exploit code is currently available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Latest version available through Microsoft Store/App Store/Google Play Store as of February 2024 security update
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21411
Restart Required: Yes
Instructions:
1. Open Skype application. 2. Check for updates in settings. 3. If update available, install immediately. 4. Restart Skype after installation. 5. For mobile devices, update through respective app stores.
🔧 Temporary Workarounds
Disable automatic media processing
allPrevent automatic processing of media files which could be used as attack vectors
Settings > Messaging > Turn off 'Automatically download media'
Network segmentation
allRestrict Skype traffic to necessary networks only
Firewall rules to restrict Skype traffic to trusted networks only
🧯 If You Can't Patch
- Disable Skype entirely until patching is possible
- Implement application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check Skype version in application settings. If version is older than February 2024 security update, system is vulnerable.Check Version:
Skype: Help > About Skype (desktop) or Settings > About (mobile)Verify Fix Applied:
Verify Skype has been updated to latest version and no longer shows update available in settings.📡 Detection & Monitoring
Log Indicators:
- Unusual process execution from Skype directory
- Suspicious network connections initiated by Skype process
- Crash logs from Skype application
Network Indicators:
- Unusual outbound connections from Skype to unknown IPs
- Large data transfers from Skype process
SIEM Query:
Process Creation where Image contains 'skype' AND CommandLine contains suspicious patterns OR Network Connection where ProcessName contains 'skype' AND DestinationPort not in (80,443,3478-3481)