CVE-2021-27435
📋 TL;DR
This vulnerability in ARM mbed OS 6.3.0 allows attackers to trigger integer wrap-around in memory allocation functions, potentially leading to arbitrary memory allocation. This could result in system crashes or remote code execution. Affected systems are those running vulnerable versions of mbed OS.
💻 Affected Systems
- ARM mbed OS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise and attacker persistence
Likely Case
System crash or denial of service due to memory corruption
If Mitigated
Limited impact with proper memory protection mechanisms and exploit mitigations
🎯 Exploit Status
Exploitation requires triggering specific memory allocation patterns
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 6.3.0 with fix PR #14408
Vendor Advisory: https://github.com/ARMmbed/mbed-os/pull/14408
Restart Required: Yes
Instructions:
1. Update mbed OS to version with fix PR #14408
2. Rebuild and redeploy affected firmware
3. Restart affected devices
🔧 Temporary Workarounds
Memory allocation limits
allImplement bounds checking on memory allocation sizes
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable devices
- Deploy memory protection mechanisms like ASLR and stack canaries
🔍 How to Verify
Check if Vulnerable:
Check mbed OS version and verify if malloc_wrapper from 6.3.0 is presentCheck Version:
Check mbed-os version in build configuration or firmware metadataVerify Fix Applied:
Verify mbed OS version is updated beyond 6.3.0 with fix PR #14408 applied📡 Detection & Monitoring
Log Indicators:
- Memory allocation failures
- System crashes
- Unexpected process termination
Network Indicators:
- Unusual traffic patterns to embedded devices
SIEM Query:
Search for memory allocation errors or system crashes on mbed OS devices