CVE-2021-27459 – This vulnerability allows attackers to upload u... (How to Fix)

Q: What is the severity of CVE-2021-27459?

CVE-2021-27459 has a CVSS score of 9.8 (CRITICAL). This vulnerability allows attackers to upload unvalidated files to Emerson Rosemount X-STREAM Gas Analyzer webservers, enabling remote code execution. Organizations using affected Emerson gas analyzer products are at risk. The vulnerability affects multiple product revisions.

📋 TL;DR

This vulnerability allows attackers to upload unvalidated files to Emerson Rosemount X-STREAM Gas Analyzer webservers, enabling remote code execution. Organizations using affected Emerson gas analyzer products are at risk. The vulnerability affects multiple product revisions.

💻 Affected Systems

Products:

Emerson Rosemount X-STREAM Gas Analyzer

Versions: Multiple revisions (specific versions not detailed in advisory)

Operating Systems: Embedded/Proprietary

Default Config Vulnerable: ⚠️ Yes

Notes: Affects webserver component of gas analyzer products. CISA advisory ICSA-21-138-01 references multiple affected revisions.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete compromise of gas analyzer systems leading to manipulation of gas analysis data, disruption of industrial processes, or lateral movement to other industrial control systems.

🟠

Likely Case

Unauthorized access to gas analyzer systems, data manipulation, or service disruption affecting industrial operations.

🟢

If Mitigated

Limited impact with proper network segmentation and access controls preventing exploitation attempts.

🌐 Internet-Facing: HIGH

🏢 Internal Only: HIGH

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Unvalidated file upload vulnerability typically requires minimal technical skill to exploit once identified.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Contact Emerson for specific patched versions

Vendor Advisory: https://www.emerson.com/documents/automation/emerson-cyber-security-notification-update-emerson-rosemount-x-stream-gas-analyzers-en-95297.pdf

Restart Required: Yes

Instructions:

1. Contact Emerson for firmware updates. 2. Apply firmware updates following Emerson's instructions. 3. Restart affected devices. 4. Verify update completion.

🔧 Temporary Workarounds

Network Segmentation

all

Isolate gas analyzers from untrusted networks using firewalls and VLANs

Access Control

all

Restrict network access to gas analyzer webservers to authorized personnel only

🧯 If You Can't Patch

Implement strict network segmentation to isolate affected devices
Monitor for unusual file upload attempts to gas analyzer webservers

🔍 How to Verify

Check if Vulnerable:

Check device firmware version against Emerson's advisory and CISA ICSA-21-138-01

Check Version:

Check device web interface or Emerson diagnostic tools for firmware version

Verify Fix Applied:

Verify firmware version matches Emerson's patched versions and test file upload functionality

📡 Detection & Monitoring

Log Indicators:

Unusual file upload attempts to gas analyzer webservers
Unexpected process execution on gas analyzer systems

Network Indicators:

HTTP POST requests with file uploads to gas analyzer IPs
Unusual outbound connections from gas analygers

SIEM Query:

source_ip="gas_analyzer_ip" AND (http_method="POST" AND uri_contains="upload")

📊 Metadata

CVE ID: CVE-2021-27459

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-434

Published: May 20, 2021

Last Updated: November 21, 2024

🔗 References

https://us-cert.cisa.gov/ics/advisories/icsa-21-138-01 Third Party Advisory,US Government Resource
https://us-cert.cisa.gov/ics/advisories/icsa-21-138-01 Third Party Advisory,US Government Resource

📤 Share & Export

📄 Export Markdown 📋 Export JSON

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