CVE-2024-42815: TP-Link RE365 Buffer Overflow Vulnerability

CVE-2024-42815 Overview

CVE-2024-42815 is a critical buffer overflow vulnerability affecting the TP-Link RE365 Wi-Fi range extender. The vulnerability exists in /usr/bin/httpd due to a lack of proper length verification for the USER_AGENT field in HTTP requests. Attackers who successfully exploit this vulnerability can cause the remote target device to crash or execute arbitrary commands, potentially gaining full control over the affected device.

Critical Impact

Remote attackers can exploit this buffer overflow to crash the device or achieve remote code execution without authentication, compromising network infrastructure security.

Affected Products

• TP-Link RE365 Firmware version V1_180213
• TP-Link RE365 Hardware version 1.0
• TP-Link RE365 Firmware (cpe:2.3:o:tp-link:re365_firmware:180213)

Discovery Timeline

• 2024-08-19 - CVE-2024-42815 published to NVD
• 2025-07-09 - Last updated in NVD database

Technical Details for CVE-2024-42815

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), a memory corruption issue that occurs when the web server daemon (httpd) processes incoming HTTP requests. The USER_AGENT header field is parsed without adequate bounds checking, allowing an attacker to provide an overly long string that overflows the allocated buffer.

The exploitation can be performed remotely over the network without requiring authentication or user interaction. The attack complexity is low, making it accessible to attackers with basic exploitation skills. A successful exploit provides complete compromise of confidentiality, integrity, and availability of the device.

Root Cause

The root cause is improper input validation in the HTTP request handling code within /usr/bin/httpd. When the server processes the USER_AGENT header from an HTTP request, it copies the header value into a fixed-size buffer without first checking if the input length exceeds the buffer capacity. This classic buffer overflow pattern allows an attacker to write beyond the allocated memory region.

Attack Vector

The attack can be launched remotely over the network by sending a malicious HTTP request to the vulnerable device. An attacker crafts an HTTP request containing an excessively long USER_AGENT header string designed to overflow the buffer. By carefully controlling the overflow data, an attacker can:

1. Overwrite adjacent memory structures to corrupt program state
2. Overwrite the return address on the stack to redirect execution flow
3. Inject and execute arbitrary shellcode on the device
4. Cause a denial of service by crashing the httpd process

Since the httpd service runs with elevated privileges on embedded devices, successful exploitation typically grants full control over the router/extender. Technical details and a proof-of-concept demonstrating this attack vector are available in the GitHub PoC Repository.

Detection Methods for CVE-2024-42815

Indicators of Compromise

• Unexpected crashes or reboots of the TP-Link RE365 device
• Abnormally large HTTP requests in network traffic logs targeting the device management interface
• HTTP requests with unusually long User-Agent headers (exceeding several hundred bytes)
• Unusual outbound connections from the range extender to unknown IP addresses

Detection Strategies

• Deploy network intrusion detection systems (IDS) with rules to detect oversized HTTP headers targeting embedded device management interfaces
• Monitor for HTTP requests with User-Agent headers exceeding normal lengths (typically over 256-512 bytes is suspicious)
• Implement network segmentation to isolate IoT devices and monitor traffic patterns
• Use SentinelOne Singularity to detect anomalous network behavior patterns associated with exploitation attempts

Monitoring Recommendations

• Enable logging on network firewalls for traffic destined to TP-Link device management ports (typically HTTP/HTTPS)
• Implement network traffic analysis to identify potential buffer overflow exploit payloads
• Monitor for repeated connection attempts or scanning activity targeting TP-Link devices on the network
• Set up alerts for device availability to detect denial of service conditions

How to Mitigate CVE-2024-42815

Immediate Actions Required

• Check TP-Link's official support site for firmware updates addressing this vulnerability
• Restrict management interface access to trusted networks only using firewall rules
• Disable remote management features if not required
• Consider placing affected devices behind a VPN for remote access scenarios
• Implement network segmentation to limit lateral movement in case of compromise

Patch Information

At the time of publication, users should check the TP-Link support website for the latest firmware updates for the RE365 range extender. Given the critical nature of this vulnerability, upgrading to the latest available firmware is strongly recommended. For detailed technical analysis, refer to the Security Online CVE Analysis.

Workarounds

• Restrict access to the device web interface to internal trusted networks only
• Implement firewall rules to block external access to the device management ports
• Place the device on an isolated network segment separate from critical infrastructure
• Monitor device behavior for signs of compromise until a patch is available

# Example: Restrict access to TP-Link device using iptables (on network firewall/gateway)
# Allow management access only from trusted admin workstation
iptables -A FORWARD -d <RE365_IP> -p tcp --dport 80 -s <TRUSTED_ADMIN_IP> -j ACCEPT
iptables -A FORWARD -d <RE365_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <RE365_IP> -p tcp --dport 443 -s <TRUSTED_ADMIN_IP> -j ACCEPT
iptables -A FORWARD -d <RE365_IP> -p tcp --dport 443 -j DROP