CVE-2025-44649

Executive Summary

CVE-2025-44649 identifies a critical misconfiguration in the TRENDnet TEW-WLC100P wireless controller (firmware version 2.03b03). The racoon IKE daemon is configured to use aggressive mode as the first exchange mode in its configuration file. Aggressive mode in IKE Phase 1 transmits identity information (e.g., IP addresses, hostnames) in plaintext, is vulnerable to offline dictionary attacks against pre-shared keys, and lacks the flexibility of main mode for negotiating security parameters. This exposes the device to identity disclosure and potential VPN credential compromise.

Impact: An attacker on the network path can capture IKE packets, extract identity information, and perform offline brute-force attacks on the pre-shared key. Successful compromise could lead to unauthorized VPN access to the internal network.

Affected Ecosystem: This is a standalone network appliance (TRENDnet TEW-WLC100P). It is not a WordPress plugin or component.

Supply Chain & Package Security

Not applicable. This is a firmware-level vulnerability in a network appliance, not a software package from NPM, PyPI, Go, or Ruby.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (NVD base score not assigned; calculated below)
• Calculated CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Base Score: 7.5 (High)
• Attack Vector: Network (AV:N) – attacker can be on the same network segment.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H) – identity and PSK hash exposed.
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: High. The vulnerability allows passive sniffing and offline cracking of VPN credentials, leading to potential network compromise.

Deep Dive & Mechanics

The racoon daemon is an IKE (Internet Key Exchange) implementation used for IPsec VPNs. IKE Phase 1 has two modes: main mode and aggressive mode.

• Main Mode: Exchanges identity information (ID payload) only after the Diffie-Hellman exchange and encryption are established. Identity is protected.
• Aggressive Mode: Sends the identity payload in the first message, before encryption is established. The identity is transmitted in plaintext. Additionally, aggressive mode uses a hash of the pre-shared key (PSK) that can be captured and used for offline dictionary attacks.

In the TRENDnet TEW-WLC100P firmware, the configuration file for racoon sets exchange_mode aggressive as the first option. This forces the IKE daemon to prefer aggressive mode, exposing the device to the following attacks:

1. Identity Disclosure: An attacker sniffing the network can see the identity (e.g., IP address, hostname) of the VPN peer.
2. Offline Dictionary Attack: The attacker captures the IKE aggressive mode exchange (including the hash of the PSK). They can then attempt to crack the PSK offline using tools like ike-scan or psk-crack.
3. Lack of Parameter Negotiation: Aggressive mode does not support the full range of security parameter negotiation, potentially allowing weaker algorithms to be used.

Attack Scenario:

1. Attacker positions themselves on the same network segment as the TEW-WLC100P (e.g., via ARP spoofing, compromised switch, or wireless sniffing).
2. Attacker captures IKE packets using tcpdump or Wireshark.
3. Attacker identifies aggressive mode exchanges and extracts the PSK hash.
4. Attacker uses ike-scan --pskcrack or John the Ripper to crack the PSK.
5. With the PSK, the attacker can authenticate as a legitimate VPN peer and access the internal network.

Vulnerable vs. Patched Code

Vulnerable Configuration (racoon.conf):

# Vulnerable: aggressive mode set as first exchange mode
exchange_mode aggressive, main;

Patched Configuration (racoon.conf):

# Patched: main mode set as first exchange mode
exchange_mode main, aggressive;

The fix is to change the order so that main is the preferred mode. This ensures identity protection and prevents offline dictionary attacks.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Attacker machine on the same network segment as the TEW-WLC100P.
• Tools: tcpdump, Wireshark, ike-scan, psk-crack (part of ike-scan), John the Ripper.

Step 1: Capture IKE Traffic

# Capture IKE packets (UDP port 500 and 4500)
tcpdump -i eth0 -w ike_capture.pcap udp port 500 or udp port 4500

Step 2: Extract Aggressive Mode Exchange

# Use ike-scan to identify aggressive mode
ike-scan --showbackoff --aggressive --id=any <target_IP>

Step 3: Crack the PSK

# Extract PSK hash from pcap
ike-scan --pskcrack --pcap=ike_capture.pcap > psk_hash.txt

# Crack with John the Ripper
john --wordlist=/usr/share/wordlists/rockyou.txt psk_hash.txt

Step 4: Establish VPN Connection

# Use strongSwan or similar to connect with cracked PSK
ipsec up vpn_connection

Blue Team

Detection:

• Monitor for IKE aggressive mode packets (ISAKMP header with exchange type = 4).
• Alert on multiple IKE Phase 1 attempts from unknown IPs.
• Use the Sigma rule below.

Hunting:

• Search for exchange_mode aggressive in device configurations.
• Check for unauthorized VPN connections from unknown peers.

Mitigation:

• Change the racoon.conf to use exchange_mode main, aggressive; (or remove aggressive entirely).
• Use certificate-based authentication instead of PSK.
• Segment the network to limit exposure of the TEW-WLC100P.

Indicators of Compromise (IOCs)

• Network IOCs:
  • IKE packets with exchange type = 4 (Aggressive Mode) in ISAKMP header.
  • UDP packets on port 500 or 4500 with plaintext identity payloads.
  • Multiple IKE SA initiation attempts from a single IP within a short time.
• Host IOCs:
  • Unauthorized IPsec SAs on the TEW-WLC100P.
  • Modified racoon.conf file (if attacker gains access).
• Log IOCs:
  • racoon logs showing aggressive mode negotiations.
  • Syslog entries: exchange_mode aggressive or phase1 aggressive.

Detection Engineering

YARA Rule

rule Detect_Aggressive_IKE_Config {
    meta:
        description = "Detects racoon.conf with aggressive mode set as first exchange mode"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-44649"
    strings:
        $config = "exchange_mode aggressive" nocase
        $main = "main" nocase
    condition:
        $config and not $main at $config
}

Sigma Rule

title: IKE Aggressive Mode Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects IKE packets using aggressive mode (exchange type 4)
author: Valters IT
date: 2025-04-10
logsource:
    category: network
    product: suricata
detection:
    selection:
        - app_proto: 'ike'
        - ike.exchange_type: '4'
    condition: selection
falsepositives:
    - Legitimate use of aggressive mode in controlled environments
level: high

Suricata Rule

alert udp any any -> any 500 (msg:"CVE-2025-44649 IKE Aggressive Mode Detected"; content:"|04|"; offset:12; depth:1; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Change Configuration: Modify /etc/racoon/racoon.conf to set exchange_mode main, aggressive; or remove aggressive entirely.
2. Restart Service: systemctl restart racoon or equivalent.
3. Use Strong Authentication: Replace PSK with certificate-based authentication (X.509).
4. Network Segmentation: Place the TEW-WLC100P in a management VLAN with strict ACLs.

Long-Term Fix:

• Contact TRENDnet for a firmware patch that defaults to main mode.
• Monitor for firmware updates at TRENDnet Support.

Workaround:

• If aggressive mode is required for compatibility, ensure the PSK is a strong, random string (e.g., 32+ characters) and rotate regularly.

Valters IT