Overview
CVE-2021-4466 identifies a critical security vulnerability affecting IPCop versions up to and including 2.1.9. This flaw allows an authenticated attacker to execute arbitrary code remotely on the affected system, potentially leading to full system compromise. The vulnerability resides within the web-based administration interface’s email configuration component.
Technical Details
The vulnerability stems from insufficient input sanitization within the email configuration component. Specifically, the application directly incorporates user-controlled values, including the EMAIL_PW parameter, into system-level operations without proper validation. This allows an attacker with valid administrative credentials to inject shell metacharacters into the email password field.
By crafting a malicious email password containing shell commands and then triggering the “save-and-test-mail” action, the attacker can execute arbitrary operating system commands. These commands are executed with the privileges of the web interface process, typically resulting in root-level access and complete system takeover.
In essence, the attack leverages a classic command injection vulnerability, where untrusted user input is directly passed to a system command interpreter.
CVSS Analysis
Unfortunately, the CVSS score and severity rating for CVE-2021-4466 are currently listed as N/A. However, based on the description of the vulnerability as a Remote Code Execution vulnerability, it is highly probable that this vulnerability would receive a CVSS score that indicates a critical severity, likely ranging from 9.0 to 10.0, due to the ease of exploitation, low skill level needed and the potential for complete system compromise.
A CVSS score in this range would reflect the high impact and exploitability of the vulnerability, emphasizing the need for immediate action.
Possible Impact
The successful exploitation of CVE-2021-4466 can have devastating consequences:
- Complete System Compromise: Attackers gain full control of the IPCop firewall system.
- Data Breach: Sensitive data stored on or passing through the firewall can be accessed and exfiltrated.
- Network Disruption: The firewall can be disabled, leading to network outages.
- Malware Installation: The attacker can install malware, backdoors, or other malicious software on the system.
- Lateral Movement: The compromised firewall can be used as a pivot point to attack other systems on the network.
Mitigation or Patch Steps
The primary mitigation strategy is to upgrade to a patched version of IPCop that addresses this vulnerability. Unfortunately, as IPCop is no longer actively maintained, official patches are unlikely. Consider the following options:
- Upgrade to a Supported Firewall Solution: The most effective solution is to migrate to a modern, actively supported firewall distribution like OPNsense or pfSense.
- Apply a Community-Developed Patch (If Available): Check for community-maintained patches, although their reliability and security should be thoroughly evaluated before deployment.
- Implement Workarounds (If Possible, but not recommended): Due to the nature of the vulnerability, effective workarounds are difficult to implement and may significantly impact functionality. Any workaround would likely involve rigorously sanitizing the `EMAIL_PW` parameter, which may be complex and risky to implement manually. Therefore, upgrading to a secure, supported firewall solution is strongly recommended.
- Network Segmentation: Implement network segmentation to limit the impact if the IPCop is compromised.
Important Note: Continuing to use an unpatched and vulnerable IPCop instance poses a significant security risk. Immediate action is required.
