CVE-2025-47149

Executive Summary

CVE-2025-47149 exposes a critical flaw in the optional 'Anti-Virus & Sandbox' feature of i-FILTER, a content filtering and security product. The vulnerability stems from improper validation of pattern files, which are used to define detection rules for malware and other threats. An attacker can craft a malicious pattern file that the product treats as authorized, leading to potential information disclosure from the server or a denial of service (DoS) condition. This issue is particularly dangerous because it bypasses the core security mechanism of the product, allowing an attacker to inject arbitrary detection logic or corrupt the scanning engine. The CVSS score of 5.3 (Medium) reflects the potential for confidentiality and availability impact, though the attack complexity is low and no privileges are required. As of this report, no official patch is available, and no public proof-of-concept (PoC) or exploit code has been released.

Supply Chain & Package Security

This vulnerability does not affect an open-source package manager (NPM, PyPI, Go, Ruby). It is a proprietary software component of i-FILTER. However, the pattern file distribution mechanism represents a supply chain risk: if the update channel or file signing process is compromised, an attacker could distribute malicious pattern files to all i-FILTER installations.

CVSS Breakdown & Threat Level

• CVSS Score: 5.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
• Attack Vector (AV): Network – The attacker can deliver the malicious pattern file over the network (e.g., via a man-in-the-middle attack or by hosting it on a compromised update server).
• Attack Complexity (AC): Low – No special conditions are required; the attacker only needs to serve a crafted file.
• Privileges Required (PR): None – The attacker does not need any authentication or prior access.
• User Interaction (UI): None – The victim does not need to click or approve anything; the product automatically processes the pattern file.
• Scope (S): Unchanged – The vulnerable component is the only affected system.
• Confidentiality (C): Low – Limited information disclosure is possible (e.g., file paths, configuration details).
• Integrity (I): None – The attacker cannot modify data, only read it or cause a crash.
• Availability (A): Low – A DoS condition can be triggered, but the product may recover after restart.

Threat Level: Medium. The lack of a patch and the low attack complexity make this a viable target for threat actors, especially in environments where i-FILTER is used for content filtering and security.

Deep Dive & Mechanics

The i-FILTER 'Anti-Virus & Sandbox' feature relies on pattern files to identify malicious content. These files are typically signed or validated to ensure they come from a trusted source. The vulnerability lies in the validation logic: the product fails to properly verify the authenticity and integrity of a pattern file before loading it.

Root Cause: Improper pattern file validation (CWE-345: Insufficient Verification of Data Authenticity). The product likely checks for a signature or hash but does so in a way that can be bypassed. For example, it may only check the file extension or a header field without cryptographic verification, or it may accept self-signed certificates from untrusted sources.

Attack Scenario:

1. An attacker crafts a malicious pattern file that contains specially crafted data.
2. The attacker delivers this file to the i-FILTER server via a network share, a compromised update server, or a man-in-the-middle attack on the update channel.
3. The i-FILTER product loads the malicious pattern file, treating it as authorized.
4. The malicious pattern file can:
   • Information Disclosure: Include pattern rules that cause the product to read and return sensitive files (e.g., /etc/passwd, configuration files) when scanning.
   • Denial of Service: Contain malformed data that triggers a crash or infinite loop in the scanning engine, rendering the product unavailable.

Impact: An attacker can gain unauthorized access to server information or disrupt the security service, potentially allowing other attacks to go undetected.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, based on the vulnerability description, the following pseudo-code illustrates the flawed validation:

Vulnerable Code (Conceptual):

def load_pattern_file(file_path):
    # Only checks file extension and a simple header
    if file_path.endswith('.pat') and read_header(file_path) == 'PATTERN_FILE':
        process_patterns(file_path)
    else:
        raise InvalidPatternFileError()

Patched Code (Conceptual):

def load_pattern_file(file_path):
    # Verify cryptographic signature using a trusted public key
    if not verify_signature(file_path, TRUSTED_PUBLIC_KEY):
        raise InvalidSignatureError()
    # Also validate file structure and content
    if not validate_pattern_structure(file_path):
        raise InvalidPatternFileError()
    process_patterns(file_path)

The patched version would require a valid digital signature from the vendor, preventing unauthorized pattern files from being loaded.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Target: i-FILTER server with 'Anti-Virus & Sandbox' enabled (version unknown).
• Attacker Machine: Kali Linux with network access to the target.
• Tools: Python, Metasploit (for payload delivery), custom script to craft malicious pattern file.

Exploitation Steps:

1. Craft Malicious Pattern File: Create a file that mimics the i-FILTER pattern file format but contains a payload for information disclosure or DoS.

   # craft_pattern.py
   import struct
   # Simple pattern file header (example)
   header = b'PATTERN_FILE\x00\x01'
   # Payload: read /etc/passwd (for information disclosure)
   payload = b'RULE: READ_FILE /etc/passwd'
   # Or for DoS: infinite loop
   # payload = b'RULE: LOOP INFINITE'
   with open('malicious.pat', 'wb') as f:
       f.write(header + payload)
   

2. Deliver the File: Use a man-in-the-middle attack (e.g., ARP spoofing) to intercept the update channel and replace the legitimate pattern file with the malicious one. Alternatively, if the product loads pattern files from a network share, place the file there.
3. Trigger Loading: Wait for the product to automatically download or load the pattern file (e.g., during a scheduled update).
4. Observe Impact: For information disclosure, monitor the product's logs or network traffic for the leaked data. For DoS, observe the product crash or become unresponsive.

Note: No public exploit code is available. The above is a conceptual demonstration.

Blue Team (Defensive)

Detection & Response:

1. Monitor Pattern File Changes: Use file integrity monitoring (FIM) to alert on any changes to pattern file directories.
2. Network Traffic Analysis: Look for unusual connections to untrusted IPs during pattern file updates.
3. Log Analysis: Check i-FILTER logs for errors related to pattern file loading or unexpected crashes.
4. Honeypot: Deploy a decoy i-FILTER server to attract attackers and analyze their techniques.

Mitigation:

• Disable the 'Anti-Virus & Sandbox' feature if not essential.
• Implement network segmentation to limit exposure of the i-FILTER server.
• Use a web application firewall (WAF) to inspect traffic to the update server.
• Apply vendor patches as soon as they become available.

Indicators of Compromise (IOCs)

• File Hashes (SHA-256): (None available, but monitor for any new .pat files with unexpected hashes)
• Network Indicators:
  • Connections to untrusted IPs on ports 80/443 (pattern file download).
  • Unusual DNS queries for domains mimicking the vendor's update server.
• Behavioral Indicators:
  • i-FILTER service crashes or restarts unexpectedly.
  • Unusual file read operations (e.g., reading /etc/passwd or other sensitive files).
  • High CPU usage from the scanning engine (possible infinite loop).
• Registry/File System:
  • New or modified files in the pattern file directory (e.g., C:\Program Files\i-FILTER\patterns\).
  • Presence of files with .pat extension that are not signed by the vendor.

Detection Engineering

YARA Rule

rule CVE_2025_47149_Malicious_Pattern_File {
    meta:
        description = "Detects malicious pattern files targeting i-FILTER Anti-Virus & Sandbox"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-47149"
    strings:
        $header = "PATTERN_FILE"
        $suspicious_rule = /RULE:\s*(READ_FILE|LOOP|EXEC)/
    condition:
        $header and $suspicious_rule
}

Sigma Rule

title: CVE-2025-47149 - i-FILTER Malicious Pattern File Loading
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects loading of unauthorized pattern files in i-FILTER
author: Valters IT
date: 2025-04-10
logsource:
    product: windows
    service: sysmon
    category: file_event
detection:
    selection:
        EventID: 11
        TargetFilename|endswith: '.pat'
        Image|contains: 'i-FILTER'
    condition: selection
falsepositives:
    - Legitimate pattern file updates from vendor
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"CVE-2025-47149 - i-FILTER Pattern File Download from Untrusted Source"; flow:to_server,established; content:"GET"; http_method; content:"/patterns/"; http_uri; content:".pat"; http_uri; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the 'Anti-Virus & Sandbox' feature if it is not critical for operations.
2. Restrict network access to the i-FILTER server, especially outbound connections to update servers.
3. Implement file integrity monitoring on pattern file directories.
4. Use a proxy or firewall to inspect and block unauthorized pattern file downloads.

Long-Term Fix:

• Apply the vendor's patch as soon as it is released.
• Consider migrating to an alternative security solution if the vendor does not provide a timely fix.

Workaround:

• Manually verify pattern file signatures using an external tool before loading them into i-FILTER.

Valters IT
DevSecOps & Cyber Threat Intelligence