CVE-2024-3780

Executive Summary

CVE-2024-3780 exposes a critical information disclosure vulnerability in the Technicolor CGA2121 router (firmware version 1.01). A local attacker with low privileges can extract sensitive Wi-Fi network credentials (SSIDs and passwords) from the device’s configuration storage. This flaw stems from improper access controls on stored data, allowing an authenticated local user to read files or memory regions containing plaintext credentials. The vulnerability has a CVSS score of 7.8 (High) due to the high confidentiality impact and low attack complexity. No public exploit code or patch is currently available, making this a significant risk for affected deployments.

Supply Chain & Package Security

This vulnerability is not related to any open-source package ecosystem (NPM, PyPI, Go, Ruby). It affects a proprietary embedded device firmware. Supply chain risks include the lack of a vendor patch and the potential for malicious actors to leverage this information disclosure for lateral movement within a network.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
• Attack Vector (AV): Local – the attacker must have physical or shell access to the device.
• Attack Complexity (AC): Low – no special conditions are required.
• Privileges Required (PR): Low – the attacker needs a standard user account on the device.
• User Interaction (UI): None – no user action is needed.
• Scope (S): Unchanged – the exploit does not affect other components.
• Confidentiality (C): High – full disclosure of Wi-Fi credentials.
• Integrity (I): None – no data modification.
• Availability (A): None – no denial of service.

Threat Level: High. The exposure of Wi-Fi credentials can lead to network compromise, data exfiltration, and further attacks on connected devices.

Deep Dive & Mechanics

The vulnerability resides in the Technicolor CGA2121’s firmware version 1.01. The device stores Wi-Fi network SSIDs and passwords in a configuration file or memory region that is readable by any local user. The root cause is a lack of proper file system permissions or encryption for sensitive data. An attacker with local access (e.g., via SSH, telnet, or a compromised web interface) can execute commands to read the configuration file (e.g., /etc/config/wireless or a similar path) or query the device’s management interface to retrieve the credentials in plaintext.

The attack flow:

1. Gain local access to the router (e.g., via default credentials, a separate vulnerability, or physical access).
2. Navigate to the configuration storage location.
3. Read the file or use a command-line tool to dump the Wi-Fi credentials.
4. Use the extracted SSID and password to connect to the Wi-Fi network.

No authentication bypass or privilege escalation is required beyond the initial local access.

Vulnerable vs. Patched Code

Since no patch is available, a comparison cannot be made. The vulnerable code likely stores credentials in a world-readable file or exposes them via an unprotected API endpoint. A patched version would:

• Encrypt stored credentials using a device-specific key.
• Restrict file permissions to root-only.
• Remove plaintext credential exposure from diagnostic or status pages.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Local access to the Technicolor CGA2121 (e.g., via SSH with default credentials admin:admin or a known backdoor).
• Knowledge of the device’s file system structure.

Exploitation Steps:

1. Connect to the device via SSH:

   ssh admin@<router_ip>
   

2. Locate the Wi-Fi configuration file (common paths):

   cat /etc/config/wireless
   cat /tmp/wifi.conf
   cat /var/run/wifi.conf
   

3. Alternatively, use the device’s command-line interface to dump credentials:

   nvram show | grep -E "ssid|password|psk"
   

4. Extract the SSID and password from the output.

Example Output:

wl0_ssid=MyNetwork
wl0_wpa_psk=SecretPassword123

Blue Team (Detection & Hardening)

Detection:

• Monitor for unauthorized SSH or telnet sessions to the router.
• Alert on commands like cat /etc/config/wireless or nvram show executed by non-root users.
• Use network segmentation to limit local access to the management interface.

Hardening:

• Change default credentials immediately.
• Disable remote management (SSH/telnet) if not required.
• Apply the vendor patch when available.
• Implement a firewall rule to restrict management access to trusted IPs only.

Indicators of Compromise (IOCs)

• File Access: Unauthorized reads of /etc/config/wireless, /tmp/wifi.conf, or /var/run/wifi.conf.
• Command Execution: Execution of nvram show or grep for SSID/password patterns.
• Network Anomalies: New devices connecting to the Wi-Fi network from unknown MAC addresses.
• Log Entries: SSH login attempts from unusual IPs or users.

Detection Engineering

YARA Rule

rule CVE_2024_3780_WiFi_Credential_Exposure {
    meta:
        description = "Detects attempts to read Wi-Fi credentials on Technicolor CGA2121"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-3780"
    strings:
        $ssid_pattern = /wl\d+_ssid=/
        $psk_pattern = /wl\d+_wpa_psk=/
        $config_path = "/etc/config/wireless"
        $nvram_cmd = "nvram show"
    condition:
        any of ($ssid_pattern, $psk_pattern) or
        ($config_path in filesystem) or
        ($nvram_cmd in command_line)
}

Sigma Rule

title: Technicolor CGA2121 Wi-Fi Credential Extraction
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects local attempts to read Wi-Fi credentials on Technicolor CGA2121
author: Valters IT
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/cat'
        CommandLine|contains: '/etc/config/wireless'
    selection2:
        Image|endswith: '/nvram'
        CommandLine|contains: 'show'
    condition: selection or selection2
falsepositives:
    - Legitimate administrative activity
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-3780 Technicolor CGA2121 Wi-Fi Credential Exfiltration"; flow:to_server,established; content:"wl0_ssid"; nocase; content:"wl0_wpa_psk"; nocase; distance:0; within:100; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Change the default administrative password on the router.
   • Disable remote management interfaces (SSH, telnet, HTTP) if not required.
   • Restrict management access to a dedicated VLAN or trusted IPs.

2. Long-Term Fix:

   • Await an official firmware patch from Technicolor. Monitor their security advisory page.
   • If no patch is released, consider replacing the device with a supported alternative.

3. Compensating Controls:

   • Implement network segmentation to isolate the router from critical assets.
   • Enable logging and monitoring for suspicious access to the router’s management interface.
   • Use a WPA2-Enterprise or WPA3 network with 802.1X authentication to reduce the impact of credential exposure.

4. Detection:

   • Deploy the provided YARA, Sigma, and Suricata rules to detect exploitation attempts.
   • Regularly audit router logs for unauthorized access.

Valters IT
DevSecOps & Cyber Threat Intelligence