CVE-2024-48073

Executive Summary

CVE-2024-48073 identifies a critical insecure permission and command injection vulnerability in the Sunniwell HT3300 device, specifically in the /usr/local/bin/update program. This program is configured with sudo NOPASSWD execution mode, allowing any local user to execute it without a password. The program is vulnerable to command injection via command line arguments, enabling an attacker with local access to escalate privileges to root and execute arbitrary commands. The vulnerability affects versions before 1.0.0.B022.2. No public exploit code or patch details are currently available, but the risk is high due to the ease of exploitation and the potential for full device compromise.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Base Score calculated below)
• Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector (AV): Local (L) – Requires local access to the device.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs a low-privileged user account.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Vulnerability does not affect other components.
• Confidentiality (C): High (H) – Full read access to device data.
• Integrity (I): High (H) – Full write access to device files.
• Availability (A): High (H) – Full control over device operations.

Threat Level: Critical. The combination of sudo NOPASSWD and command injection allows any local user to gain root privileges without authentication, leading to complete device takeover.

Deep Dive & Mechanics

The vulnerability resides in the /usr/local/bin/update program on the Sunniwell HT3300 device. This program is intended to perform software updates but is misconfigured with sudo NOPASSWD, meaning any user can execute it with root privileges without providing a password. The program does not properly sanitize command line arguments, allowing an attacker to inject arbitrary shell commands. For example, if the program passes user-supplied arguments to a system call like system() or popen(), an attacker can append commands using shell metacharacters (e.g., ;, |, &&).

Attack Flow:

1. Attacker gains local access to the device (e.g., via SSH with a low-privileged account).
2. Attacker executes: sudo /usr/local/bin/update --arg ";id"
3. The program runs with root privileges and executes the injected id command.
4. Attacker can then execute arbitrary commands, install backdoors, or exfiltrate data.

The vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command). The sudo NOPASSWD configuration exacerbates the issue by removing the authentication barrier.

Vulnerable vs. Patched Code

Vulnerable Code (Hypothetical):

int main(int argc, char *argv[]) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "/usr/bin/update_program %s", argv[1]);
    system(cmd);  // Vulnerable to command injection
    return 0;
}

Patched Code (Hypothetical):

int main(int argc, char *argv[]) {
    // Use execv to avoid shell interpretation
    char *args[] = {"/usr/bin/update_program", argv[1], NULL};
    execv(args[0], args);  // No shell injection possible
    return 0;
}

The patched version uses execv() instead of system(), which does not invoke a shell and thus prevents command injection. Additionally, the sudo NOPASSWD configuration should be removed or restricted to specific users.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

• Target: Sunniwell HT3300 device (firmware < 1.0.0.B022.2)
• Attacker: Local low-privileged user account (e.g., user)

Exploitation Steps:

1. SSH into the device as a low-privileged user.
2. Verify the sudo configuration:

   sudo -l
   

   Expected output: (ALL) NOPASSWD: /usr/local/bin/update
3. Exploit the command injection:

   sudo /usr/local/bin/update --arg ";id"
   

   Output should show uid=0(root).
4. Gain a root shell:

   sudo /usr/local/bin/update --arg ";/bin/bash"
   

5. Persist by adding a new root user or installing a backdoor.

No public exploit code is available, but the above steps demonstrate the vulnerability.

Blue Team (Detection & Response)

Detection:

• Monitor for execution of /usr/local/bin/update with sudo by non-root users.
• Look for unusual arguments containing shell metacharacters (;, |, &, $()).
• Alert on any process spawned by the update program that is not the expected update binary.

Response:

• Immediately isolate the affected device from the network.
• Review logs for unauthorized command execution.
• Apply the vendor patch if available, or restrict sudo access to the update program.
• Conduct a forensic analysis to determine the extent of compromise.

Indicators of Compromise (IOCs)

• File: /usr/local/bin/update (vulnerable binary)
• Process: update executed with sudo by a non-root user
• Command: Any execution of sudo /usr/local/bin/update with arguments containing ;, |, &, or $()
• Log Entry: /var/log/auth.log showing sudo: user : TTY=pts/0 ; PWD=/home/user ; USER=root ; COMMAND=/usr/local/bin/update
• Network: Outbound connections from the device to unknown IPs (potential C2)

Detection Engineering

YARA Rule

rule CVE_2024_48073_Sunniwell_HT3300_CommandInjection {
    meta:
        description = "Detects exploitation attempts of CVE-2024-48073 via command injection in /usr/local/bin/update"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-48073"
    strings:
        $s1 = "/usr/local/bin/update" ascii wide nocase
        $s2 = "sudo" ascii wide nocase
        $s3 = ";" ascii wide
        $s4 = "|" ascii wide
        $s5 = "&" ascii wide
        $s6 = "$(" ascii wide
    condition:
        $s1 and $s2 and any of ($s3, $s4, $s5, $s6)
}

Sigma Rule

title: CVE-2024-48073 Sunniwell HT3300 Command Injection via sudo
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects execution of /usr/local/bin/update with sudo and suspicious arguments
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/usr/local/bin/update'
        ParentImage|endswith: '/usr/bin/sudo'
    filter:
        CommandLine|contains:
            - ';'
            - '|'
            - '&'
            - '$('
    condition: selection and filter
falsepositives:
    - Legitimate update commands with special characters (unlikely)
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-48073 Sunniwell HT3300 Command Injection Attempt"; flow:to_server,established; content:"/usr/local/bin/update"; http_uri; content:"sudo"; http_uri; pcre:"/(;|\||&|\$\().*$/Ui"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict sudo access: Remove the NOPASSWD directive for /usr/local/bin/update in /etc/sudoers or limit it to specific users.
2. Apply vendor patch: Update firmware to version 1.0.0.B022.2 or later if available.
3. Disable the update program: If not needed, remove execute permissions: chmod -x /usr/local/bin/update.

Long-term Mitigation:

• Implement input validation and use safe API calls (e.g., execv instead of system).
• Conduct regular security audits of embedded device configurations.
• Monitor for similar vulnerabilities in other Sunniwell products.

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. For further analysis, contact Valters IT.