Comprehensive Technical Analysis of CVE-2023-37710

CVE ID: CVE-2023-37710 CVSS Score: 9.8 (Critical) Affected Products: Tenda AC1206 (V15.03.06.23), Tenda AC10 (V15.03.06.47) Vulnerability Type: Stack-Based Buffer Overflow

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1. Vulnerability Assessment and Severity Evaluation

Technical Overview

CVE-2023-37710 is a stack-based buffer overflow vulnerability in Tenda’s wireless router firmware, specifically in the wpapsk_crypto parameter within the fromSetWirelessRepeat function. The flaw arises due to improper bounds checking when processing user-supplied input, allowing an attacker to overwrite adjacent memory structures on the stack.

Severity Justification (CVSS 9.8 - Critical)

The CVSS v3.1 scoring breakdown is as follows:

• Attack Vector (AV:N) – Network-exploitable (remote attack surface).
• Attack Complexity (AC:L) – Low complexity; no special conditions required.
• Privileges Required (PR:N) – No authentication needed (pre-authentication exploit).
• User Interaction (UI:N) – No user interaction required.
• Scope (S:C) – Changes scope (impacts confidentiality, integrity, and availability).
• Confidentiality (C:H), Integrity (I:H), Availability (A:H) – High impact across all three security pillars.

This vulnerability is remotely exploitable without authentication, making it highly attractive for threat actors seeking to compromise home or small business networks.

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2. Potential Attack Vectors and Exploitation Methods

Exploitation Mechanism

1. Input Manipulation:

   • The fromSetWirelessRepeat function processes the wpapsk_crypto parameter, which is likely part of a wireless repeater configuration request (e.g., via HTTP POST).
   • An attacker crafts a maliciously oversized input (e.g., a long WPA-PSK key) that exceeds the buffer’s allocated size, triggering a stack overflow.

2. Memory Corruption & Code Execution:

   • The overflow corrupts the return address on the stack, allowing arbitrary code execution (ACE) in the context of the router’s firmware.
   • If ASLR (Address Space Layout Randomization) and stack canaries are absent (common in embedded devices), exploitation is trivial.

3. Payload Delivery:

   • Attackers may inject shellcode to:
     • Establish a reverse shell (e.g., via telnetd or nc).
     • Deploy persistent malware (e.g., Mirai-like botnet agents).
     • Modify DNS settings for phishing or MITM attacks.
     • Disable security features (e.g., firewall rules).

Attack Scenarios

Scenario	Description	Impact
Remote Code Execution (RCE)	Exploit via crafted HTTP request to the router’s web interface.	Full device takeover, lateral movement in the network.
Botnet Recruitment	Compromise multiple Tenda routers to form a DDoS botnet.	Large-scale DDoS attacks, network congestion.
Credential Theft	Exfiltrate stored Wi-Fi passwords or admin credentials.	Unauthorized network access, further attacks on connected devices.
DNS Hijacking	Modify router DNS settings to redirect users to malicious sites.	Phishing, malware distribution, or ad fraud.
Firmware Backdooring	Persistently modify firmware to maintain access even after reboots.	Long-term espionage or data exfiltration.

Exploit Availability

• Proof-of-Concept (PoC) Exploits are publicly available on GitHub (FirmRec/IoT-Vulns), lowering the barrier for attackers.
• Metasploit Module may emerge, further simplifying exploitation.

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3. Affected Systems and Software Versions

Vulnerable Products

Product	Vulnerable Firmware Version	Fixed Version (if available)
Tenda AC1206	V15.03.06.23	Not yet patched
Tenda AC10	V15.03.06.47	Not yet patched

Detection Methods

• Network Scanning:
  • Use Nmap to identify Tenda routers:

    nmap -p 80,443 --script http-title 192.168.1.0/24 | grep "Tenda"
    

• Firmware Analysis:
  • Extract firmware using Binwalk and analyze the fromSetWirelessRepeat function for buffer overflow vulnerabilities.
• Vulnerability Scanners:
  • Nessus, OpenVAS, or Tenable.io may include detection plugins for this CVE.

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4. Recommended Mitigation Strategies

Immediate Actions

Mitigation	Implementation Details	Effectiveness
Disable Remote Management	Restrict web interface access to LAN-only (disable WAN access).	High
Change Default Credentials	Replace default admin:admin with a strong, unique password.	Medium
Network Segmentation	Isolate IoT devices (including routers) in a separate VLAN.	High
Disable WPS & UPnP	Prevent unauthorized device pairing and port forwarding.	High
Apply Firewall Rules	Block inbound traffic to ports 80/443 from external sources.	Medium

Long-Term Remediation

1. Firmware Updates:

   • Monitor Tenda’s official website for patches (no fix available as of analysis).
   • If no patch is released, consider replacing the device with a supported model.

2. Intrusion Detection/Prevention (IDS/IPS):

   • Deploy Snort/Suricata rules to detect exploitation attempts:

     alert tcp any any -> $HOME_NET 80 (msg:"Tenda Router Stack Overflow Attempt"; flow:to_server,established; content:"wpapsk_crypto="; pcre:"/wpapsk_crypto=.{100,}/"; sid:1000001; rev:1;)
     

3. Firmware Hardening:

   • If custom firmware (e.g., OpenWRT) is an option, replace the stock firmware to eliminate the vulnerability.

4. Zero Trust Network Access (ZTNA):

   • Enforce strict access controls for all devices, requiring authentication even on the LAN.

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5. Impact on the Cybersecurity Landscape

Broader Implications

1. IoT Security Crisis:

   • This vulnerability highlights the persistent lack of security in consumer-grade IoT devices, particularly routers.
   • Supply chain risks are exacerbated when vendors fail to patch known flaws.

2. Botnet Proliferation:

   • Unpatched Tenda routers are prime targets for botnets (e.g., Mirai, Mozi), contributing to DDoS attacks and ransomware campaigns.

3. Regulatory & Compliance Risks:

   • Organizations using affected routers may violate data protection laws (e.g., GDPR, CCPA) if breaches occur due to unpatched devices.

4. Exploit Chaining:

   • Attackers may combine this flaw with other vulnerabilities (e.g., CVE-2023-XXXX) to escalate privileges or bypass security controls.

Threat Actor Motivations

Actor Type	Likely Exploitation Goals
Cybercriminals	Botnet recruitment, ransomware delivery, credential theft.
APT Groups	Persistent access for espionage or lateral movement.
Script Kiddies	Bragging rights, defacement, or simple disruption.
Hacktivists	Disrupting services for political or ideological reasons.

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6. Technical Details for Security Professionals

Root Cause Analysis

• Vulnerable Function: fromSetWirelessRepeat (likely in /bin/httpd or /bin/webs).
• Flaw: The wpapsk_crypto parameter is copied into a fixed-size stack buffer without proper length validation.
• Example Exploit Trigger:

  POST /goform/fromSetWirelessRepeat HTTP/1.1
  Host: 192.168.0.1
  Content-Type: application/x-www-form-urlencoded
  Content-Length: [MALICIOUS_LENGTH]
  
  wpapsk_crypto=[A*1000]&other_params=...
  

  • The A*1000 payload overflows the buffer, corrupting the stack.

Exploitation Requirements

Requirement	Details
Target Access	LAN or WAN (if remote management is enabled).
Authentication	None (pre-authentication exploit).
Exploit Reliability	High (if ASLR/stack canaries are disabled, which is common in embedded systems).
Shellcode Execution	Possible via ROP (Return-Oriented Programming) if DEP is enabled.

Reverse Engineering Insights

1. Firmware Extraction:
   • Use Binwalk to extract the firmware:

     binwalk -e Tenda_AC1206_V15.03.06.23.bin
     

2. Binary Analysis:
   • Load the extracted httpd binary in Ghidra or IDA Pro.
   • Locate fromSetWirelessRepeat and analyze the wpapsk_crypto handling.
3. Dynamic Analysis:
   • Use QEMU to emulate the router’s firmware and debug the overflow:

     qemu-mipsel -g 1234 ./httpd
     

   • Attach GDB to analyze memory corruption.

Detection & Forensics

• Log Analysis:
  • Check router logs (/var/log/messages or /tmp/log) for unusual fromSetWirelessRepeat requests.
• Memory Forensics:
  • Use Volatility (if applicable) to detect injected shellcode in memory dumps.
• Network Traffic Analysis:
  • Look for oversized HTTP POST requests to /goform/fromSetWirelessRepeat.

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Conclusion & Recommendations

CVE-2023-37710 represents a critical, remotely exploitable vulnerability in widely deployed Tenda routers. Given the public availability of PoC exploits and the lack of immediate patches, organizations and consumers must take proactive mitigation steps to prevent compromise.

Key Takeaways for Security Teams

✅ Immediately disable remote management and segment IoT devices. ✅ Monitor for exploitation attempts using IDS/IPS rules. ✅ Replace unsupported devices if no patch is forthcoming. ✅ Assume breach and hunt for signs of compromise in network traffic.

Final Risk Assessment

Factor	Risk Level	Justification
Exploitability	Critical	Remote, unauthenticated, low complexity.
Impact	Critical	Full device takeover, network compromise.
Patch Availability	High Risk	No patch available; vendor response unknown.
Threat Actor Interest	High	Public PoCs, botnet recruitment potential.

Action Priority: URGENT – Apply mitigations immediately and monitor for updates from Tenda.

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References:

• MITRE CVE-2023-37710
• FirmRec IoT-Vulns GitHub
• NVD Entry