CVE-2024-5400: Openfind Mail2000 RCE Vulnerability

CVE-2024-5400 Overview

CVE-2024-5400 is a command injection vulnerability in Openfind Mail2000, a widely deployed email server platform. The product fails to properly filter parameters passed to specific Common Gateway Interface (CGI) endpoints. Authenticated remote attackers holding regular user privileges can inject operating system commands through these parameters. Successful exploitation results in arbitrary command execution on the underlying server with the privileges of the web application.

The issue is classified under [CWE-78] (Improper Neutralization of Special Elements used in an OS Command).

Critical Impact
Authenticated attackers can execute arbitrary system commands on Mail2000 servers, leading to full compromise of the mail platform, exposure of stored messages, and potential lateral movement into adjacent systems.

Affected Products

Openfind Mail2000 version 6.0
Openfind Mail2000 version 7.0
Openfind Mail2000 version 8.0

Discovery Timeline

2024-05-27 - CVE-2024-5400 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-5400

Vulnerability Analysis

Mail2000 exposes several CGI scripts that accept HTTP request parameters and pass those parameters to underlying operating system commands. The affected CGI handlers do not sanitize or validate the supplied input before concatenating it into command strings executed by the host shell. This design flaw allows an attacker to inject shell metacharacters such as ;, |, &&, or backticks into request parameters. The injected payload is then interpreted by the shell, executing attacker-controlled commands within the context of the Mail2000 web service account.

Because Mail2000 is typically internet-facing to support webmail access, the CGI endpoints are reachable across the network. Exploitation requires only a regular authenticated session, which lowers the practical barrier when credentials are phished, reused, or provisioned to a large user base.

Root Cause

The root cause is improper neutralization of special elements used in an operating system command [CWE-78]. The vulnerable CGI logic constructs shell command strings from untrusted HTTP parameter values without applying allowlist validation, argument-array execution, or safe escaping.

Attack Vector

An authenticated attacker sends a crafted HTTP request to the vulnerable CGI endpoint on the Mail2000 web interface. The request embeds shell metacharacters and a chained command within a parameter value. The server-side handler passes the tainted value to a shell invocation, and the operating system executes the injected command. Attackers can use this primitive to establish reverse shells, drop web shells inside the Mail2000 web root, dump mail store data, or pivot to internal infrastructure.

No verified proof-of-concept has been published. See the Taiwan CERT Advisory for vendor-coordinated details.

Detection Methods for CVE-2024-5400

Indicators of Compromise

HTTP requests to Mail2000 CGI endpoints containing shell metacharacters such as ;, |, &, $(), or backticks in parameter values.
Unexpected child processes spawned by the Mail2000 web server process, such as sh, bash, wget, curl, nc, or python.
New or modified files written into the Mail2000 web root, including unfamiliar .cgi, .pl, or .sh files.
Outbound network connections initiated by the mail server process to unfamiliar external hosts.

Detection Strategies

Deploy web application firewall rules that inspect Mail2000 CGI parameters for shell metacharacters and command keywords.
Enable process-lineage monitoring to alert when the Mail2000 CGI handler forks shell interpreters or network utilities.
Correlate authenticated Mail2000 session events with subsequent process-creation and outbound-connection telemetry from the host.

Monitoring Recommendations

Forward Mail2000 web server access logs and host process telemetry to a centralized analytics platform for retention and correlation.
Alert on any CGI request producing an HTTP 200 response that is followed within seconds by a new outbound socket from the web service account.
Baseline the normal set of child processes for the Mail2000 service and flag deviations as high-priority events.

How to Mitigate CVE-2024-5400

Immediate Actions Required

Apply the vendor-supplied patch for Mail2000 as referenced in the Taiwan CERT Advisory.
Restrict access to the Mail2000 administrative and CGI endpoints to trusted networks or VPN clients until patching is complete.
Rotate credentials for all Mail2000 accounts, prioritizing administrative and service accounts, in case existing sessions were abused.
Review Mail2000 hosts for signs of prior exploitation, including unexpected web shells, cron entries, and outbound connections.

Patch Information

Openfind has published fixed builds for Mail2000. Administrators should consult the Taiwan CERT Advisory and coordinate directly with Openfind support to obtain patched versions applicable to their deployed 6.0, 7.0, or 8.0 release line.

Workarounds

Place the Mail2000 web interface behind a reverse proxy or WAF that blocks shell metacharacters in CGI parameter values.
Disable or restrict access to non-essential CGI endpoints until patches are deployed.
Enforce network segmentation so the Mail2000 host cannot initiate arbitrary outbound connections to the internet.

bash

# Example WAF rule concept: block shell metacharacters in Mail2000 CGI parameters
# (Adapt to your WAF syntax; validate against legitimate traffic before enforcing.)
SecRule ARGS "@rx [;|&`$()<>]|\\$\\(|\\|\\||&&" \
    "id:1005400,phase:2,deny,status:403,\
    msg:'Potential command injection targeting Mail2000 CGI (CVE-2024-5400)',\
    tag:'CVE-2024-5400'"