CVE-2021-21871 – This vulnerability allows an attacker to execut... (How to Fix)

Q: What is the severity of CVE-2021-21871?

CVE-2021-21871 has a CVSS score of 7.8 (HIGH). This vulnerability allows an attacker to execute arbitrary code on systems running vulnerable versions of PowerISO by tricking users into opening a specially crafted DMG file. The memory corruption via out-of-bounds write can lead to complete system compromise. Users of PowerISO 7.9 and potentially earlier versions are affected.

📋 TL;DR

This vulnerability allows an attacker to execute arbitrary code on systems running vulnerable versions of PowerISO by tricking users into opening a specially crafted DMG file. The memory corruption via out-of-bounds write can lead to complete system compromise. Users of PowerISO 7.9 and potentially earlier versions are affected.

💻 Affected Systems

Products:

PowerISO

Versions: PowerISO 7.9 and earlier versions

Operating Systems: Windows

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems where PowerISO is installed and configured to handle DMG files.

📦 What is this software?

Poweriso by Poweriso

View all CVEs affecting Poweriso →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with SYSTEM/root privileges leading to complete host takeover, data theft, and lateral movement within the network.

🟠

Likely Case

Local privilege escalation or arbitrary code execution in the context of the user opening the malicious DMG file.

🟢

If Mitigated

Limited impact if DMG files from untrusted sources are blocked or PowerISO is not used for DMG processing.

🌐 Internet-Facing: MEDIUM

🏢 Internal Only: HIGH

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires user interaction to open a malicious DMG file. The vulnerability is well-documented with technical details available.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: PowerISO 7.9 bug-release (specific version number not specified in CVE)

Vendor Advisory: https://www.poweriso.com/

Restart Required: No

Instructions:

1. Download latest PowerISO version from official website. 2. Run installer to update. 3. Verify version is post-7.9 bug-fix release.

🔧 Temporary Workarounds

Disable DMG file association

windows

Remove PowerISO as default handler for DMG files to prevent automatic exploitation

Control Panel > Default Programs > Set Default Programs > Select another program for .dmg files

Block DMG files at perimeter

all

Prevent DMG files from entering the network via email or web downloads

🧯 If You Can't Patch

Implement application whitelisting to block PowerISO execution
Educate users to never open DMG files from untrusted sources

🔍 How to Verify

Check if Vulnerable:

Check PowerISO version in Help > About. If version is 7.9 or earlier, system is vulnerable.

Check Version:

PowerISO.exe --version or check in Help > About dialog

Verify Fix Applied:

Verify PowerISO version is updated to post-7.9 bug-fix release. Test with known safe DMG files.

📡 Detection & Monitoring

Log Indicators:

PowerISO crash logs
Windows Application Error events related to PowerISO
Unexpected DMG file processing

Network Indicators:

DMG file downloads from untrusted sources
Unusual outbound connections after DMG file access

SIEM Query:

EventID=1000 OR EventID=1001 Source="PowerISO" OR ProcessName="PowerISO.exe" AND FileExtension=".dmg"

📊 Metadata

CVE ID: CVE-2021-21871

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-787

Published: June 29, 2021

Last Updated: November 21, 2024

🔗 References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1308 Exploit,Third Party Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1308 Exploit,Third Party Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2021-21871, you might also want to check these: