CVE-2018-17161 in FreeBSD
Summary
by MITRE
In FreeBSD before 11.2-STABLE(r348229), 11.2-RELEASE-p7, 12.0-STABLE(r342228), and 12.0-RELEASE-p1, insufficient validation of network-provided data in bootpd may make it possible for a malicious attacker to craft a bootp packet which could cause a stack buffer overflow. It is possible that the buffer overflow could lead to a Denial of Service or remote code execution.
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Analysis
by VulDB Data Team • 04/26/2020
The vulnerability identified as CVE-2018-17161 affects FreeBSD operating systems prior to specific stable and release versions, representing a critical security flaw in the bootpd service responsible for handling bootstrap protocol packets. This issue stems from inadequate validation mechanisms within the network boot process implementation, where the system fails to properly sanitize incoming bootp packets from network sources. The flaw specifically manifests in the handling of user-supplied data during the boot process, creating an avenue for malicious actors to exploit the system through crafted network traffic.
The technical implementation of this vulnerability involves a stack buffer overflow condition that occurs when bootpd processes malformed bootp packets containing oversized or improperly formatted data fields. The insufficient input validation allows attackers to exceed the allocated buffer space in memory, potentially corrupting adjacent stack memory locations. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions. The flaw demonstrates poor memory management practices where the system does not adequately check the length of incoming data before copying it into fixed-size buffers, creating an exploitable condition that can be triggered through network communication.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it presents potential for remote code execution capabilities that could allow attackers to gain unauthorized control over affected systems. When exploited successfully, the buffer overflow could enable malicious actors to inject and execute arbitrary code within the context of the bootpd service, potentially leading to complete system compromise. This vulnerability affects systems running FreeBSD versions before 11.2-STABLE(r348229), 11.2-RELEASE-p7, 12.0-STABLE(r342228), and 12.0-RELEASE-p1, making it particularly concerning for organizations maintaining older FreeBSD installations. The attack surface is significant as bootpd services are commonly enabled on network infrastructure devices, servers, and systems that rely on network boot capabilities, making them attractive targets for exploitation.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected FreeBSD systems to the latest stable releases containing the necessary security fixes. Organizations should also implement network segmentation and access controls to limit exposure of bootpd services to trusted networks only, reducing the attack surface available to potential attackers. Additional defensive measures include monitoring network traffic for suspicious bootp packet patterns and implementing intrusion detection systems that can identify anomalous bootpd behavior. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving command and control communications and privilege escalation through service exploitation, making it particularly dangerous when combined with other attack vectors. System administrators should also consider disabling bootpd services entirely if network boot functionality is not required, following the principle of least privilege and reducing potential attack surfaces within their environments.