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CVE-2021-2279

8.1 HIGH
Remote Code Execution

📋 TL;DR

This vulnerability in Oracle VM VirtualBox allows an unauthenticated attacker with network access via RDP to potentially take over the VirtualBox instance. It affects VirtualBox versions prior to 6.1.20 and can lead to complete compromise of the virtualization software.

💻 Affected Systems

Products:
  • Oracle VM VirtualBox
Versions: All versions prior to 6.1.20
Operating Systems: All platforms running VirtualBox
Default Config Vulnerable: ⚠️ Yes
Notes: Requires RDP access to be enabled/available on VirtualBox instance.

📦 What is this software?

Vm Virtualbox by Oracle

View all CVEs affecting Vm Virtualbox →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete takeover of Oracle VM VirtualBox, allowing attacker to execute arbitrary code, access all virtual machines, and compromise the host system.

🟠

Likely Case

Remote code execution on the VirtualBox host, potentially leading to data theft, VM escape, or denial of service.

🟢

If Mitigated

Limited impact if VirtualBox is not exposed to untrusted networks and RDP access is restricted.

🌐 Internet-Facing: HIGH - Network accessible via RDP with unauthenticated exploitation potential.
🏢 Internal Only: MEDIUM - Still significant risk if internal network access is available to attackers.

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ⚠️ Yes
Complexity: HIGH

Oracle describes as 'difficult to exploit' but unauthenticated network access via RDP is required.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 6.1.20 or later

Vendor Advisory: https://www.oracle.com/security-alerts/cpuapr2021.html

Restart Required: Yes

Instructions:

1. Download VirtualBox 6.1.20 or later from Oracle website. 2. Stop all running VMs. 3. Uninstall current VirtualBox version. 4. Install updated version. 5. Restart host system.

🔧 Temporary Workarounds

Disable RDP Access

all

Disable Remote Desktop Protocol access to VirtualBox instances

VBoxManage modifyvm <vmname> --vrde off

Network Segmentation

all

Restrict network access to VirtualBox RDP ports (default 3389)

iptables -A INPUT -p tcp --dport 3389 -j DROP
netsh advfirewall firewall add rule name="Block VirtualBox RDP" dir=in action=block protocol=TCP localport=3389

🧯 If You Can't Patch

  • Disable RDP access on all VirtualBox instances
  • Implement strict network segmentation and firewall rules to block RDP access from untrusted networks

🔍 How to Verify

Check if Vulnerable:

Check VirtualBox version: VBoxManage --version or via GUI Help → About VirtualBox

Check Version:

VBoxManage --version

Verify Fix Applied:

Confirm version is 6.1.20 or higher using VBoxManage --version

📡 Detection & Monitoring

Log Indicators:

  • Unusual RDP connection attempts to VirtualBox
  • Failed authentication attempts via RDP
  • Unexpected process execution from VirtualBox components

Network Indicators:

  • RDP traffic to VirtualBox hosts from unexpected sources
  • Anomalous network patterns on port 3389

SIEM Query:

source="virtualbox.log" AND "RDP" AND ("failed" OR "unauthorized") OR destination_port=3389 AND source_ip NOT IN [trusted_ips]

📊 Metadata

CVE ID: CVE-2021-2279
CVSS v3 Score: 8.1 (HIGH)
CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: April 22, 2021
Last Updated: November 21, 2024

🔗 References

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