CVE-2020-15692
📋 TL;DR
This vulnerability in Nim's standard library allows argument injection through the browsers.openDefaultBrowser function. Attackers can pass malicious local file paths that get executed as system commands, potentially leading to remote code execution. Applications using Nim 1.2.4 or earlier with the browsers module are affected.
💻 Affected Systems
- Nim programming language
📦 What is this software?
Nim by Nim Lang
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with system-level privileges, allowing complete compromise of affected systems and potential lateral movement.
Likely Case
Local privilege escalation or arbitrary command execution in applications that process untrusted URLs through the vulnerable function.
If Mitigated
Limited impact if input validation prevents malicious arguments from reaching the vulnerable function.
🎯 Exploit Status
Exploitation requires the application to pass user-controlled input to the vulnerable function. The vulnerability is well-documented with public proof-of-concept examples.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Nim 1.2.6 and 1.0.8
Vendor Advisory: https://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.html
Restart Required: No
Instructions:
1. Update Nim to version 1.2.6 or later. 2. Recompile all Nim applications with the updated compiler. 3. Redeploy patched applications.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation to prevent malicious arguments from reaching the browsers.openDefaultBrowser function
Disable or replace browsers module
allRemove or replace usage of the browsers module with alternative implementations that properly sanitize input
🧯 If You Can't Patch
- Implement strict input validation on all user inputs passed to the browsers module
- Use application sandboxing or privilege separation to limit potential damage from exploitation
🔍 How to Verify
Check if Vulnerable:
Check if your Nim application uses the browsers module and calls openDefaultBrowser with user-controlled input. Review source code for imports of 'browsers' module.Check Version:
nim --versionVerify Fix Applied:
Verify Nim version is 1.2.6 or later using 'nim --version'. Recompile application with updated compiler and test with malicious inputs.📡 Detection & Monitoring
Log Indicators:
- Unusual process executions from Nim applications
- Suspicious command-line arguments passed to system commands
Network Indicators:
- Unexpected outbound connections from Nim applications
SIEM Query:
Process creation where parent process contains 'nim' and command line contains unusual arguments or file paths🔗 References
- http://www.openwall.com/lists/oss-security/2021/02/04/1
- https://consensys.net/diligence/vulnerabilities/nim-browsers-argument-injection/
- https://github.com/nim-lang/Nim/blob/dc5a40f3f39c6ea672e6dc6aca7f8118a69dda99/lib/pure/browsers.nim#L48
- https://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.html
- http://www.openwall.com/lists/oss-security/2021/02/04/1
- https://consensys.net/diligence/vulnerabilities/nim-browsers-argument-injection/
- https://github.com/nim-lang/Nim/blob/dc5a40f3f39c6ea672e6dc6aca7f8118a69dda99/lib/pure/browsers.nim#L48
- https://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.html
