CVE-2020-24338
📋 TL;DR
This vulnerability in picoTCP's DNS implementation allows attackers to send specially crafted DNS responses that trigger out-of-bounds writes, potentially leading to denial-of-service or remote code execution. It affects systems using picoTCP library versions through 1.7.0 for network communications. The high CVSS score indicates critical impact potential.
💻 Affected Systems
- picoTCP embedded TCP/IP stack
📦 What is this software?
Picotcp by Altran
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with full system compromise, allowing attacker to execute arbitrary code on vulnerable systems.
Likely Case
Denial-of-service causing system crashes or instability in affected network services.
If Mitigated
Limited impact if network segmentation prevents malicious DNS responses from reaching vulnerable systems.
🎯 Exploit Status
Exploitation requires sending malicious DNS responses to vulnerable systems, which can be done remotely without authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version after 1.7.0
Vendor Advisory: https://us-cert.cisa.gov/ics/advisories/icsa-20-343-01
Restart Required: Yes
Instructions:
1. Update picoTCP library to version after 1.7.0. 2. Recompile applications using the library. 3. Restart affected services or devices.
🔧 Temporary Workarounds
Disable DNS functionality
allIf DNS is not required, disable DNS client functionality in picoTCP configuration
Modify picoTCP configuration to disable DNS support
Network filtering
allBlock or filter incoming DNS responses at network perimeter
Configure firewall rules to restrict DNS traffic to trusted sources only
🧯 If You Can't Patch
- Segment network to isolate vulnerable systems from untrusted DNS sources
- Implement strict firewall rules allowing DNS only from trusted internal resolvers
🔍 How to Verify
Check if Vulnerable:
Check picoTCP library version in use. If version is 1.7.0 or earlier, system is vulnerable.Check Version:
Check application documentation or build configuration for picoTCP version informationVerify Fix Applied:
Verify picoTCP library version is updated beyond 1.7.0 and applications have been recompiled with updated library.📡 Detection & Monitoring
Log Indicators:
- Application crashes, memory corruption errors, abnormal DNS response handling
Network Indicators:
- Unusual DNS response patterns, malformed DNS packets to vulnerable systems
SIEM Query:
dns AND (response AND malformed OR corruption) OR application_crash AND picoTCP