MEDIUM CVSS 6.5
Published: 2021-04-22

CVE-2020-27738

siemens simotics_connect_400_firmware Security Advisory (CVE-2020-27738)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2020-27738 impacting siemens simotics_connect_400_firmware. Evaluated with CVSS Base Score of 6.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.3), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a read access past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product siemens / simotics_connect_400_firmware
Affected Versions *
Weakness Enumeration CWE-788

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2020-27738 impacting siemens simotics_connect_400_firmware.

⚡ Nuclei Detection Template (YAML) cve-2020-27738.yaml
id: cve-2020-27738

info:
  name: siemens simotics_connect_400_firmware - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2020-27738 affecting siemens simotics_connect_400_firmware.
    Evaluation: A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions &lt; V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions &lt; V2....
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2020-27738
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
    cvss-score: 6.5
    cve-id: CVE-2020-27738
    cwe-id: CWE-788
  tags: cve,cve-2020-27738,siemens,simotics_connect_400_firm,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "simotics_connect_400_firmware"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2020-27738.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2020-27738
# Target: siemens simotics_connect_400_firmware | CVSS: 6.5 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2020-27738 (siemens simotics_connect_400_firmware)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against siemens simotics_connect_400_firmware scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2020-27738.sh
# Recommended Remediation & Patching Commands for CVE-2020-27738
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install simotics_connect_400_firm 2>/dev/null || \
sudo dnf upgrade simotics_connect_400_firm 2>/dev/null || \
sudo yum update simotics_connect_400_firm

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i simotics_connect_400_firm 2>/dev/null || rpm -qa | grep -i simotics_connect_400_firm

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2020-27738 in siemens simotics_connect_400_firmware?

Review vendor-specific security notices and update siemens simotics_connect_400_firmware packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2020-27738?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2020-27738?

CVE-2020-27738 is classified with a CVSS 3.1 Base Score of 6.5 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
6.5
MEDIUM SEVERITY
CVE ID CVE-2020-27738
Weakness CWE-788
Vendor siemens
Product simotics_connect_400_firmware
Published 2021-04-22
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H