CVE-2021-27419
📋 TL;DR
CVE-2021-27419 is an integer overflow vulnerability in uClibc-ng's malloc-simple functions that can lead to arbitrary memory allocation. This could cause crashes or potentially allow remote code execution. It affects embedded systems and IoT devices using vulnerable uClibc-ng versions.
💻 Affected Systems
- uClibc-ng
📦 What is this software?
Uclibc Ng by Uclibc Ng Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise and attacker persistence on affected devices.
Likely Case
Application crashes and denial of service due to memory corruption, potentially leading to device instability.
If Mitigated
Limited impact with proper memory protections and exploit mitigations in place.
🎯 Exploit Status
Exploitation requires triggering the vulnerable malloc-simple functions with specific inputs.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.37 and later
Vendor Advisory: https://downloads.uclibc-ng.org/releases/
Restart Required: Yes
Instructions:
1. Download uClibc-ng 1.0.37 or later from official releases. 2. Rebuild affected applications with patched library. 3. Replace vulnerable uClibc-ng library on target systems. 4. Restart affected services or devices.
🔧 Temporary Workarounds
Memory hardening
linuxEnable ASLR and other memory protection mechanisms
echo 2 > /proc/sys/kernel/randomize_va_space
Input validation
allImplement strict input validation in applications using malloc-simple
🧯 If You Can't Patch
- Network segmentation to isolate vulnerable devices
- Implement strict access controls and monitoring for affected systems
🔍 How to Verify
Check if Vulnerable:
Check uClibc-ng version on system: ldd --version or check library filesCheck Version:
strings /lib/libc.so.0 | grep 'uclibc'Verify Fix Applied:
Verify uClibc-ng version is 1.0.37 or later and applications have been rebuilt📡 Detection & Monitoring
Log Indicators:
- Application crashes
- Memory allocation errors
- Segmentation faults
Network Indicators:
- Unusual outbound connections from embedded devices
- Traffic spikes to/from IoT devices
SIEM Query:
source="*" ("segmentation fault" OR "malloc" OR "memory allocation") AND ("uclibc" OR "embedded")