CVE-2025-47901

Executive Summary

CVE-2025-47901 is a critical OS Command Injection vulnerability in Microchip Time Provider 4100, a network time server appliance. The vulnerability exists in versions prior to 2.5 and allows an unauthenticated attacker to inject arbitrary operating system commands through improper neutralization of special elements. This can lead to full compromise of the device, including data exfiltration, lateral movement, and disruption of time synchronization services. No public proof-of-concept or exploit code is currently available, and the EPSS score is 0.0%, indicating low exploitation activity at this time. The vendor has not released a patch, but version 2.5 is expected to resolve the issue.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects a hardware appliance (Microchip Time Provider 4100) and its embedded firmware.

CVSS Breakdown & Threat Level

The CVSS vector is not provided in the NVD data. However, based on the nature of the vulnerability (OS Command Injection in a network-accessible appliance), a reasonable assessment is:

• Attack Vector (AV): Network (N) – The vulnerability is 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) – The vulnerable component is the only affected component.
• Confidentiality (C): High (H) – Full system access possible.
• Integrity (I): High (H) – Full system modification possible.
• Availability (A): High (H) – Service disruption possible.

Estimated CVSS v3.1 Score: 9.8 (Critical)

Threat Level: Critical – Remote, unauthenticated command execution on a network appliance.

Deep Dive & Mechanics

The vulnerability is an OS Command Injection (CWE-78) in the Microchip Time Provider 4100. The device likely accepts user input (e.g., via web interface, SNMP, or CLI) that is improperly sanitized before being passed to a system shell. An attacker can inject shell metacharacters (e.g., ;, |, &, `, $()) to execute arbitrary commands.

Attack Vector: The most likely attack vector is through the web management interface, where parameters such as NTP server addresses, time zone settings, or administrative commands are not properly validated. An attacker could send a crafted HTTP request containing command injection payloads.

Impact: Successful exploitation allows the attacker to:

• Execute arbitrary commands with the privileges of the web server (often root).
• Install backdoors, exfiltrate configuration files, or pivot to internal networks.
• Disrupt time synchronization, affecting dependent systems (e.g., authentication, logging).

Vulnerable vs. Patched Code

No specific code snippets are available. However, the vulnerable code likely resembles:

# Vulnerable (pseudo-code)
import subprocess
user_input = request.GET.get('ntp_server')
subprocess.call("ntpdate " + user_input, shell=True)

The patched version (2.5) should use parameterized commands or proper input validation:

# Patched (pseudo-code)
import subprocess
user_input = request.GET.get('ntp_server')
# Validate input (e.g., IP address format)
if is_valid_ip(user_input):
    subprocess.call(["ntpdate", user_input])
else:
    raise ValueError("Invalid input")

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A vulnerable Microchip Time Provider 4100 (version < 2.5) in a lab environment.
• Network access to the device's management interface (typically HTTP/HTTPS on port 80/443).

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /cgi-bin/ntp_config).
2. Inject command: ; id or | whoami.
3. Example HTTP request:

   POST /cgi-bin/ntp_config HTTP/1.1
   Host: 192.168.1.100
   Content-Type: application/x-www-form-urlencoded
   Content-Length: 50
   
   ntp_server=pool.ntp.org;id
   

4. Observe output in response or via out-of-band exfiltration (e.g., DNS).

No public exploit code is available. The above is a hypothetical example.

Blue Team (Defensive)

Detection:

• Monitor for unusual HTTP requests containing shell metacharacters (;, |, &, `).
• Look for outbound connections from the Time Provider to unexpected IPs/domains.
• Check for unauthorized changes to NTP configuration.

Hunting:

• Search logs for patterns like ntp_server=*;* or ntp_server=*|*.
• Use network flow data to detect anomalous traffic from the device.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests containing shell metacharacters in parameters (e.g., ntp_server=*;id).
  • Outbound connections from the device to unknown IPs on non-standard ports.
• Host:
  • Unexpected processes running on the device (e.g., reverse shells).
  • Modified system binaries or configuration files.
  • New user accounts or SSH keys.
• Logs:
  • Web server logs showing POST requests with suspicious payloads.
  • System logs showing command execution events (e.g., audit.log).

Detection Engineering

YARA Rule

rule CVE_2025_47901_OS_Command_Injection {
    meta:
        description = "Detects OS command injection attempts against Microchip Time Provider 4100"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-47901"
    strings:
        $cmd1 = /ntp_server=.*[;&|`$()]/
        $cmd2 = /timezone=.*[;&|`$()]/
        $cmd3 = /admin_cmd=.*[;&|`$()]/
    condition:
        any of them
}

Sigma Rule

title: CVE-2025-47901 OS Command Injection Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects HTTP requests with shell metacharacters targeting Microchip Time Provider 4100
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - 'ntp_server='
            - 'timezone='
            - 'admin_cmd='
        cs-uri-query|re: '.*[;&|`$()].*'
    condition: selection
falsepositives:
    - Legitimate use of special characters in input (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-47901 OS Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"ntp_server="; http_client_body; pcre:"/[;&|`$()]/R"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade to version 2.5 or later as soon as it becomes available.
2. Restrict network access to the management interface (e.g., firewall rules, VPN).
3. Disable the web interface if not required, or use HTTPS with strong authentication.

Long-term Measures:

• Implement input validation and parameterized commands in all web-facing components.
• Conduct regular security audits and penetration testing.
• Monitor vendor advisories for patches.

Workarounds (if patching is not possible):

• Use a reverse proxy to filter malicious payloads (e.g., ModSecurity with OWASP CRS).
• Isolate the device on a separate VLAN with strict egress controls.

Valters IT
DevSecOps & Cyber Threat Intelligence