CVE-2023-50432 in simple-dhcp-server
Summary
by MITRE • 04/30/2024
simple-dhcp-server through ec976d2 allows remote attackers to cause a denial of service (daemon crash) by sending a DHCP packet without any option fields, which causes free_packet in dhcp_packet.c to dereference a NULL pointer.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 11/20/2024
The vulnerability identified as CVE-2023-50432 affects the simple-dhcp-server software version up to and including ec976d2, presenting a critical denial of service condition that can be exploited remotely by attackers. This flaw resides in the packet processing logic of the DHCP daemon where the software fails to properly validate incoming DHCP packets before attempting to process them. The specific technical issue occurs when the daemon receives a DHCP packet that contains no option fields, which represents a valid but minimal DHCP packet structure that should be handled gracefully by the server software.
The core technical flaw manifests in the free_packet function within dhcp_packet.c, which attempts to dereference a NULL pointer when processing these malformed packets. This NULL pointer dereference represents a classic software vulnerability pattern that can lead to immediate daemon termination and system unavailability. The vulnerability stems from inadequate input validation and error handling within the DHCP packet parsing routines, where the software assumes that all received packets will contain valid option fields without proper null checks. This type of vulnerability is classified under CWE-476 as Null Pointer Dereference, which is a well-documented weakness in software development practices that occurs when a program attempts to access memory through a pointer that has not been initialized to a valid memory address.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers to systematically crash the DHCP daemon without requiring any authentication or privileged access. This makes the vulnerability particularly dangerous in network environments where DHCP services are critical for network operations, as it can lead to widespread network outages and service interruptions. The attack vector is straightforward and requires minimal technical expertise, making it attractive to threat actors seeking to disrupt network services. The vulnerability affects any system running the vulnerable version of simple-dhcp-server, regardless of network configuration or security measures in place, as the attack can be executed from any location capable of sending DHCP packets to the target system.
Mitigation strategies should focus on immediate software updates to versions that address the NULL pointer dereference issue through proper input validation and error handling mechanisms. Network administrators should implement monitoring solutions to detect unusual DHCP packet patterns and potential exploitation attempts, while also ensuring that DHCP services are properly isolated within network segments to limit the impact of successful attacks. The vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and represents a common pattern of exploitation targeting service availability rather than data confidentiality or integrity. Organizations should also consider implementing rate limiting and packet filtering rules at network boundaries to prevent excessive DHCP traffic from reaching vulnerable systems, while maintaining detailed logging of DHCP transactions for forensic analysis purposes.