CVE-2023-39914
📋 TL;DR
The bcder library from NLnet Labs up to version 0.7.2 contains a vulnerability where decoding certain invalid input data causes a panic instead of properly rejecting it with an error. This affects applications using bcder for ASN.1/BER/DER decoding, potentially leading to denial of service. Developers and systems using bcder for certificate parsing, network protocols, or data serialization are affected.
💻 Affected Systems
- NLnet Labs bcder library
📦 What is this software?
Bcder by Nlnetlabs
⚠️ Risk & Real-World Impact
Worst Case
Remote denial of service causing application crashes and service disruption when processing maliciously crafted ASN.1 data.
Likely Case
Application crashes or instability when encountering malformed ASN.1 data in network traffic or file processing.
If Mitigated
Minimal impact with proper input validation and error handling wrappers around bcder calls.
🎯 Exploit Status
Exploitation requires sending malformed ASN.1 data to applications using bcder. No authentication needed if application accepts external input.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 0.7.3 and later
Vendor Advisory: https://nlnetlabs.nl/downloads/bcder/CVE-2023-39914.txt
Restart Required: Yes
Instructions:
1. Update bcder dependency to version 0.7.3 or later. 2. Rebuild and redeploy affected applications. 3. Restart services using the updated library.
🔧 Temporary Workarounds
Input validation wrapper
allImplement input validation and error handling around bcder decoding calls to catch panics
Process isolation
allRun bcder-dependent processes in isolated containers with restart policies
🧯 If You Can't Patch
- Implement rate limiting and input sanitization for ASN.1 data processing
- Deploy monitoring and automatic restart mechanisms for affected services
🔍 How to Verify
Check if Vulnerable:
Check if application uses bcder library version <= 0.7.2 via dependency management files or by examining linked libraries.Check Version:
Check package manager (e.g., 'cargo tree | grep bcder' for Rust) or examine Cargo.toml/package.json for bcder version.Verify Fix Applied:
Verify bcder version is >= 0.7.3 in dependency files and test with known malformed ASN.1 test cases.📡 Detection & Monitoring
Log Indicators:
- Application panic/crash logs mentioning bcder or ASN.1 decoding
- Unexpected process terminations during data parsing
Network Indicators:
- Unusual patterns of ASN.1/BER/DER data being sent to services
- Repeated connection attempts with malformed data
SIEM Query:
Process termination events from applications known to use bcder library