CVE-2021-32944 – This vulnerability allows attackers to execute ... (How to Fix)

Q: What is the severity of CVE-2021-32944?

CVE-2021-32944 has a CVSS score of 7.8 (HIGH). This vulnerability allows attackers to execute arbitrary code or cause denial-of-service by exploiting a use-after-free memory corruption flaw in Siemens Drawings SDK when processing malicious DGN files. It affects all versions prior to 2022.4, potentially impacting any application that uses this SDK for CAD file processing.

📋 TL;DR

This vulnerability allows attackers to execute arbitrary code or cause denial-of-service by exploiting a use-after-free memory corruption flaw in Siemens Drawings SDK when processing malicious DGN files. It affects all versions prior to 2022.4, potentially impacting any application that uses this SDK for CAD file processing.

💻 Affected Systems

Products:

Siemens Drawings SDK
Applications using Siemens Drawings SDK

Versions: All versions prior to 2022.4

Operating Systems: Windows, Linux

Default Config Vulnerable: ⚠️ Yes

Notes: Any application that uses the vulnerable SDK to process DGN files is affected, regardless of the application's own version.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with the same privileges as the application using the Drawings SDK, potentially leading to complete system compromise.

🟠

Likely Case

Application crash (denial-of-service) when processing specially crafted DGN files, disrupting CAD-related workflows.

🟢

If Mitigated

Limited impact if proper network segmentation and file validation controls prevent malicious DGN files from reaching vulnerable systems.

🌐 Internet-Facing: MEDIUM - Requires user interaction to open malicious files, but web applications accepting DGN uploads could be vulnerable.

🏢 Internal Only: HIGH - Internal users could be tricked into opening malicious DGN files via email or network shares.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires user interaction to open a malicious DGN file. No public exploit code is available, but the vulnerability is well-documented.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 2022.4 or later

Vendor Advisory: https://cert-portal.siemens.com/productcert/pdf/ssa-155599.pdf

Restart Required: Yes

Instructions:

1. Identify applications using Siemens Drawings SDK. 2. Update to Drawings SDK version 2022.4 or later. 3. Restart affected applications. 4. Recompile applications if using SDK as a library.

🔧 Temporary Workarounds

Block DGN file processing

all

Prevent applications from processing DGN files entirely

Application sandboxing

all

Run CAD applications in restricted environments with limited privileges

🧯 If You Can't Patch

Implement strict file validation to reject suspicious DGN files
Network segmentation to isolate systems using vulnerable SDK

🔍 How to Verify

Check if Vulnerable:

Check if any applications use Siemens Drawings SDK version earlier than 2022.4

Check Version:

Check application documentation or contact vendor for version information

Verify Fix Applied:

Verify Drawings SDK version is 2022.4 or later and applications have been restarted

📡 Detection & Monitoring

Log Indicators:

Application crashes when processing DGN files
Memory access violation errors in application logs

Network Indicators:

Unusual DGN file transfers to vulnerable systems

SIEM Query:

Application:Drawings_SDK AND (EventID:1000 OR ExceptionCode:c0000005)

📊 Metadata

CVE ID: CVE-2021-32944

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-416

Published: June 17, 2021

Last Updated: November 21, 2024

🔗 References

https://cert-portal.siemens.com/productcert/pdf/ssa-155599.pdf Patch,Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-365397.pdf Patch,Third Party Advisory
https://us-cert.cisa.gov/ics/advisories/icsa-21-159-02 Third Party Advisory,US Government Resource
https://www.zerodayinitiative.com/advisories/ZDI-21-987/ Third Party Advisory,VDB Entry
https://www.zerodayinitiative.com/advisories/ZDI-21-990/ Third Party Advisory,VDB Entry
https://cert-portal.siemens.com/productcert/pdf/ssa-155599.pdf Patch,Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-365397.pdf Patch,Third Party Advisory
https://us-cert.cisa.gov/ics/advisories/icsa-21-159-02 Third Party Advisory,US Government Resource
https://www.zerodayinitiative.com/advisories/ZDI-21-987/ Third Party Advisory,VDB Entry
https://www.zerodayinitiative.com/advisories/ZDI-21-990/ Third Party Advisory,VDB Entry

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