CVE-2024-7490 Overview
CVE-2024-7490 is a critical improper input validation vulnerability affecting Microchip Technology's Advanced Software Framework (ASF). The vulnerability exists within the example DHCP server implementation and can be exploited to achieve remote code execution through a buffer overflow. This flaw is specifically associated with the tinydhcpserver.C program file and the lwip_dhcp_find_option routine.
The vulnerability is particularly concerning because ASF is no longer being actively supported by Microchip, meaning no official patch will be released. Organizations using affected versions must apply the provided workaround or migrate to an actively maintained framework.
Critical Impact
Remote attackers can exploit this buffer overflow vulnerability to execute arbitrary code on vulnerable systems running the ASF DHCP server implementation, potentially leading to complete system compromise.
Affected Products
- Microchip Advanced Software Framework through version 3.52.0.2574
- Systems utilizing the tinydhcpserver.C DHCP server example code
- Embedded devices implementing the lwip_dhcp_find_option routine
Discovery Timeline
- 2024-08-08 - CVE-2024-7490 published to NVD
- 2025-09-29 - Last updated in NVD database
Technical Details for CVE-2024-7490
Vulnerability Analysis
This vulnerability stems from improper input validation in the DHCP server example code included with Microchip's Advanced Software Framework. The flaw specifically resides in the lwip_dhcp_find_option routine within tinydhcpserver.C, where insufficient bounds checking on DHCP option data allows an attacker to trigger a buffer overflow condition.
When processing malformed DHCP packets, the vulnerable routine fails to properly validate the length of incoming option fields before copying data into fixed-size memory buffers. This classic buffer overflow condition (CWE-120) enables attackers to overwrite adjacent memory regions, potentially corrupting control flow data and enabling arbitrary code execution.
The network-accessible nature of DHCP services means that any device on the same network segment as a vulnerable system could potentially exploit this vulnerability without authentication.
Root Cause
The root cause is a classic buffer copy operation without proper size checking (CWE-120: Buffer Copy without Checking Size of Input). The lwip_dhcp_find_option function in tinydhcpserver.C does not adequately validate the length of DHCP options before processing them, allowing an attacker to supply oversized option data that exceeds the allocated buffer boundaries. This lack of input validation creates the conditions necessary for a buffer overflow attack.
Attack Vector
The attack vector is network-based, targeting the DHCP server functionality. An attacker positioned on the same network segment as a vulnerable device can craft malicious DHCP packets containing specially formatted option fields with excessive length values. When the vulnerable DHCP server processes these packets, the oversized data overflows the destination buffer, potentially allowing the attacker to:
- Corrupt memory structures adjacent to the buffer
- Overwrite return addresses or function pointers
- Inject and execute arbitrary code with the privileges of the DHCP server process
- Gain complete control of the affected embedded system
The attack requires no authentication and can be launched by any device capable of sending UDP packets to the DHCP server port (typically UDP port 67).
Detection Methods for CVE-2024-7490
Indicators of Compromise
- Unusual DHCP traffic patterns with oversized or malformed option fields
- Unexpected crashes or restarts of the DHCP server process
- Memory corruption artifacts in system logs or crash dumps
- Anomalous network behavior from embedded devices running ASF
Detection Strategies
- Implement network intrusion detection rules to identify malformed DHCP packets with abnormally large option lengths
- Monitor for DHCP traffic anomalies including packets exceeding typical size thresholds
- Deploy deep packet inspection to validate DHCP option field lengths against RFC specifications
- Audit systems for the presence of vulnerable tinydhcpserver.C implementations
Monitoring Recommendations
- Enable comprehensive logging on network devices to capture DHCP transaction details
- Configure alerts for repeated DHCP server process crashes or unexpected restarts
- Monitor embedded device behavior for signs of compromise such as unusual network connections or process execution
- Regularly scan the network for devices running vulnerable ASF versions
How to Mitigate CVE-2024-7490
Immediate Actions Required
- Identify all systems and devices using Microchip Advanced Software Framework version 3.52.0.2574 or earlier
- Evaluate whether the example DHCP server code (tinydhcpserver.C) is in use within your environment
- Apply network segmentation to limit exposure of vulnerable DHCP implementations
- Consider disabling the vulnerable DHCP server functionality if not essential to operations
Patch Information
Microchip has announced that Advanced Software Framework is no longer being supported, and no official patch will be released for this vulnerability. Organizations must apply the provided workaround or migrate to an actively maintained framework. For more information, consult the Microchip Software Framework Resource page and the CERT Vulnerability Advisory #138043.
Workarounds
- Migrate from the deprecated Advanced Software Framework to an actively maintained alternative
- Implement input validation wrappers around the lwip_dhcp_find_option function to enforce strict bounds checking
- Use a dedicated, hardened DHCP server instead of the example ASF implementation
- Restrict network access to DHCP services using firewalls or VLANs to limit the attack surface
# Network segmentation example - isolate vulnerable DHCP server
# Add firewall rules to restrict DHCP traffic to trusted network segments only
# iptables example to restrict DHCP access
iptables -A INPUT -p udp --dport 67 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p udp --dport 67 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
