CVE-2021-27429 – This CVE describes an integer overflow vulnerab... (How to Fix)

Q: What is the severity of CVE-2021-27429?

CVE-2021-27429 has a CVSS score of 7.4 (HIGH). This CVE describes an integer overflow vulnerability in Texas Instruments TI-RTOS's HeapTrack_alloc function that can lead to heap corruption and potential code execution. It affects embedded systems using TI-RTOS, particularly in industrial control and IoT devices. Attackers could exploit this to gain control of affected devices.

📋 TL;DR

This CVE describes an integer overflow vulnerability in Texas Instruments TI-RTOS's HeapTrack_alloc function that can lead to heap corruption and potential code execution. It affects embedded systems using TI-RTOS, particularly in industrial control and IoT devices. Attackers could exploit this to gain control of affected devices.

💻 Affected Systems

Products:

Texas Instruments TI-RTOS

Versions: Versions prior to the fix (specific version not specified in CVE description)

Operating Systems: Embedded systems using TI-RTOS

Default Config Vulnerable: ⚠️ Yes

Notes: Affects devices using TI-RTOS heap tracking functionality. Industrial control systems, IoT devices, and embedded medical devices may be impacted.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete device compromise, allowing attackers to manipulate industrial processes or steal sensitive data from embedded systems.

🟠

Likely Case

Denial of service through heap corruption causing device crashes or instability in industrial control systems.

🟢

If Mitigated

Limited impact if proper network segmentation and access controls prevent exploitation attempts.

🌐 Internet-Facing: MEDIUM - Many affected devices may be deployed in industrial networks with limited internet exposure, but IoT deployments could be directly accessible.

🏢 Internal Only: HIGH - Industrial control systems using TI-RTOS are often critical infrastructure where exploitation could disrupt operations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires triggering the integer overflow with specific large values, but detailed exploitation techniques are not publicly documented.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Updated TI-RTOS versions (specific version should be checked in vendor advisory)

Vendor Advisory: https://www.ti.com/tool/TI-RTOS-MCU

Restart Required: Yes

Instructions:

1. Check TI advisory for specific patched versions. 2. Update TI-RTOS to the latest version. 3. Recompile and redeploy firmware on affected devices. 4. Test functionality after update.

🔧 Temporary Workarounds

Disable heap tracking

all

If heap tracking is not required, disable HeapTrack functionality to remove the vulnerable code path.

Modify TI-RTOS configuration to set HeapTrack_enable = false

Input validation

all

Implement bounds checking on memory allocation requests before passing to HeapTrack_alloc.

Add validation: if (requested_size > MAX_SAFE_SIZE) return NULL;

🧯 If You Can't Patch

Implement network segmentation to isolate affected devices from untrusted networks
Deploy application allowlisting to prevent unauthorized code execution

🔍 How to Verify

Check if Vulnerable:

Check TI-RTOS version against vendor advisory. Review code for HeapTrack_alloc usage with large allocation requests.

Check Version:

Check firmware version or TI-RTOS build information in device documentation

Verify Fix Applied:

Verify TI-RTOS version is updated per vendor recommendations. Test with large allocation requests to ensure proper error handling.

📡 Detection & Monitoring

Log Indicators:

Unexpected device reboots
Heap corruption errors in system logs
Memory allocation failures

Network Indicators:

Unusual network traffic to industrial control devices
Protocol anomalies in device communications

SIEM Query:

Device:vendor="Texas Instruments" AND (event:memory_allocation_failure OR event:device_crash)

📊 Metadata

CVE ID: CVE-2021-27429

CVSS v3 Score: 7.4 (HIGH)

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

CWE: CWE-190

Published: November 20, 2023

Last Updated: November 21, 2024

🔗 References

https://www.cisa.gov/news-events/ics-advisories/icsa-21-119-04 Third Party Advisory,US Government Resource
https://www.ti.com/tool/TI-RTOS-MCU Product
https://www.cisa.gov/news-events/ics-advisories/icsa-21-119-04 Third Party Advisory,US Government Resource
https://www.ti.com/tool/TI-RTOS-MCU Product

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