Source: cve@mitre.org
Buffer overflow in bootpd on OpenBSD, FreeBSD, and Linux systems via a malformed header type.
Critical vulnerability exists in bootpd implementations on OpenBSD, FreeBSD, and Linux systems, allowing for remote code execution. A malformed header type in a DHCP request can trigger a buffer overflow, potentially granting attackers complete control over the affected server.
Step 1: Malformed DHCP Request Creation: An attacker crafts a malicious DHCP request. This request includes a DHCP option with a header type that is intentionally designed to be larger than the allocated buffer in the bootpd service.
Step 2: Request Transmission: The attacker sends the crafted DHCP request to the vulnerable bootpd server, typically on UDP port 67 or 68.
Step 3: Packet Reception and Processing: The bootpd service receives the malicious DHCP request and begins processing it.
Step 4: Header Type Parsing and Buffer Overflow: The service parses the DHCP options, including the malformed header type. Due to the lack of proper bounds checking, the service attempts to copy the oversized data associated with the header type into a fixed-size buffer. This write operation overflows the buffer.
Step 5: Code Execution: The buffer overflow overwrites critical memory areas, such as the return address on the stack. The attacker can then control the program's execution flow by overwriting the return address with the address of malicious code (shellcode) or by redirecting execution to other parts of the program that can be exploited.
The vulnerability stems from a buffer overflow within the bootpd service. Specifically, the service fails to properly validate the size of the data associated with a DHCP header type. When a crafted DHCP request with an oversized header type is received, the service attempts to write data beyond the allocated buffer, leading to memory corruption. This allows an attacker to overwrite critical memory regions, including the return address, and redirect program execution to attacker-controlled code. The root cause is a lack of bounds checking on the size of the data read from the incoming DHCP packet, leading to the overflow.
While no specific APT groups are definitively linked to this specific CVE, the nature of the vulnerability (remote code execution) makes it attractive to various threat actors. It's likely that any group seeking to gain initial access or escalate privileges on a network could leverage this vulnerability if present. CISA KEV status: Not Listed
Monitor network traffic for unusual DHCP requests, especially those with large or malformed option lengths. Use network intrusion detection systems (NIDS) with rules tailored to detect malformed DHCP packets.
Analyze DHCP server logs for errors or unusual activity, such as unexpected crashes or restarts.
Examine system logs for evidence of bootpd crashes or unexpected behavior.
Implement host-based intrusion detection systems (HIDS) to monitor file integrity and detect any unauthorized modifications to system binaries or configuration files.
Use memory analysis tools to examine the bootpd process for signs of buffer overflows or memory corruption.
Apply security patches provided by the vendor for the affected operating systems (OpenBSD, FreeBSD, and Linux).
Disable the bootpd service if it is not required. If the service is required, ensure it is running the latest patched version.
Implement network segmentation to limit the impact of a successful exploit. Isolate the DHCP server from other critical network resources.
Regularly audit and update system configurations to ensure security best practices are followed.
Implement a robust vulnerability scanning program to identify and address security weaknesses in a timely manner.
Harden the DHCP server by limiting access to only authorized clients and implementing strong authentication mechanisms.