CVE-2021-43637
📋 TL;DR
This vulnerability is a buffer overflow in the Amazon WorkSpaces agent's IOCTL handler that allows local attackers to execute arbitrary code with kernel privileges or cause denial of service through memory corruption. It affects users of Amazon WorkSpaces with vulnerable agent versions. Attackers need local access to exploit this vulnerability.
💻 Affected Systems
- Amazon WorkSpaces agent
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via kernel-mode arbitrary code execution leading to full administrative control, data theft, and persistent backdoor installation.
Likely Case
Privilege escalation from a standard user to SYSTEM/root level, enabling lateral movement and further exploitation within the environment.
If Mitigated
Limited impact if proper patch management and least privilege principles are followed, potentially only causing service disruption.
🎯 Exploit Status
Exploitation requires local access and crafting of specific IOCTL requests. The vulnerability was disclosed by security researchers with technical details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v1.0.1.1537 and later
Vendor Advisory: https://aws.amazon.com/security/security-bulletins/
Restart Required: Yes
Instructions:
1. Update Amazon WorkSpaces agent to version 1.0.1.1537 or later. 2. Restart the WorkSpaces instance. 3. Verify the update through the agent's version check.
🔧 Temporary Workarounds
Restrict local user access
allLimit local user accounts on WorkSpaces instances to reduce attack surface.
Disable USB redirection
allDisable USB-over-Ethernet functionality if not required.
🧯 If You Can't Patch
- Implement strict access controls to limit who has local access to WorkSpaces instances.
- Monitor for unusual process behavior or privilege escalation attempts using endpoint detection tools.
🔍 How to Verify
Check if Vulnerable:
Check the Amazon WorkSpaces agent version. If below 1.0.1.1537, the system is vulnerable.Check Version:
On Windows: Check 'Programs and Features' for Amazon WorkSpaces agent version. On Linux: Check package manager or agent logs.Verify Fix Applied:
Confirm the agent version is 1.0.1.1537 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Unusual IOCTL requests to the WorkSpaces driver
- Process crashes in WorkSpaces agent
- Privilege escalation events
Network Indicators:
- Local system calls to vulnerable driver interfaces
SIEM Query:
Process creation events where parent process is WorkSpaces agent with unusual command line arguments