CVE-2022-1106
📋 TL;DR
CVE-2022-1106 is a use-after-free vulnerability in mrb_vm_exec in mruby, a lightweight Ruby implementation. This vulnerability allows attackers to execute arbitrary code or cause denial of service by exploiting memory corruption. Anyone using mruby versions prior to 3.2 is affected.
💻 Affected Systems
- mruby
📦 What is this software?
Mruby by Mruby
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Application crash causing denial of service, potentially leading to data corruption or service disruption.
If Mitigated
Limited impact with proper memory protections and exploit mitigations like ASLR and DEP.
🎯 Exploit Status
Proof-of-concept exists in public repositories. Exploitation requires crafting malicious Ruby code.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: mruby 3.2 and later
Vendor Advisory: https://github.com/mruby/mruby/commit/7f5a490d09f4d56801ac3a3e4e39e03e1471b44c
Restart Required: Yes
Instructions:
1. Update mruby to version 3.2 or later. 2. Recompile any applications using mruby. 3. Restart affected services.
🔧 Temporary Workarounds
Input Validation
allImplement strict input validation to prevent malicious Ruby code from reaching mruby interpreter.
Memory Protection
linuxEnable ASLR, DEP, and other memory protection mechanisms at OS level.
echo 2 > /proc/sys/kernel/randomize_va_space
sysctl -w kernel.exec-shield=1
🧯 If You Can't Patch
- Isolate mruby applications in restricted network segments with minimal privileges.
- Implement application allowlisting to prevent execution of unauthorized mruby processes.
🔍 How to Verify
Check if Vulnerable:
Check mruby version with 'mruby --version' or examine application dependencies.Check Version:
mruby --versionVerify Fix Applied:
Confirm mruby version is 3.2 or later and verify the commit 7f5a490d09f4d56801ac3a3e4e39e03e1471b44c is included.📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes
- Memory access violation errors in system logs
- Abnormal process termination
Network Indicators:
- Unusual network connections from mruby processes
- Suspicious payloads containing Ruby code
SIEM Query:
source="*mruby*" AND (event_type="crash" OR error="segmentation fault")