CVE-2021-30139
📋 TL;DR
This vulnerability in Alpine Linux's apk-tools package manager allows a buffer overflow when parsing malicious tarball files, potentially leading to application crashes or arbitrary code execution. It affects Alpine Linux systems using apk-tools before version 2.12.5. The vulnerability can be triggered by processing specially crafted APK package files.
💻 Affected Systems
- Alpine Linux apk-tools
📦 What is this software?
Apk Tools by Alpinelinux
Apk Tools by Alpinelinux
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the apk-tools process, potentially leading to full system compromise if apk-tools runs with elevated privileges.
Likely Case
Denial of service through application crashes when processing malicious package files, disrupting package management operations.
If Mitigated
Limited impact if apk-tools runs with minimal privileges and proper input validation is in place elsewhere.
🎯 Exploit Status
Exploitation requires crafting a malicious tarball file that triggers the buffer overflow, which requires understanding of the tarball parser implementation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.12.5 and later
Vendor Advisory: https://gitlab.alpinelinux.org/alpine/apk-tools/-/issues/10741
Restart Required: No
Instructions:
1. Update apk-tools: 'apk update && apk upgrade apk-tools' 2. Verify installation: 'apk --version' should show 2.12.5 or higher
🔧 Temporary Workarounds
Restrict package sources
linuxOnly use trusted APK repositories and avoid processing packages from untrusted sources.
Edit /etc/apk/repositories to include only trusted repositories
🧯 If You Can't Patch
- Run apk-tools with minimal privileges using principle of least privilege
- Implement strict input validation for any tarball processing in custom applications
🔍 How to Verify
Check if Vulnerable:
Run 'apk --version' and check if version is below 2.12.5Check Version:
apk --versionVerify Fix Applied:
Run 'apk --version' and confirm version is 2.12.5 or higher📡 Detection & Monitoring
Log Indicators:
- Segmentation fault or crash logs from apk-tools processes
- Unexpected termination of package management operations
Network Indicators:
- Unusual network traffic to/from package repositories
- Downloads of unusually large or malformed package files
SIEM Query:
process.name:"apk" AND (event.action:"segmentation_fault" OR event.action:"crash")