CVE-2016-2148 in BusyBox
Summary
by MITRE
Heap-based buffer overflow in the DHCP client (udhcpc) in BusyBox before 1.25.0 allows remote attackers to have unspecified impact via vectors involving OPTION_6RD parsing.
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Analysis
by VulDB Data Team • 11/12/2022
The vulnerability identified as CVE-2016-2148 represents a critical heap-based buffer overflow affecting the DHCP client component known as udhcpc within BusyBox versions prior to 1.25.0. This flaw resides in the handling of OPTION_6RD parsing, which is part of the DHCP protocol implementation used for IPv6 address assignment and configuration. The vulnerability specifically manifests when the DHCP client processes malformed or specially crafted DHCP OPTION_6RD messages received from remote servers, creating a condition where memory allocation occurs without proper bounds checking.
The technical exploitation of this vulnerability occurs through improper input validation during the parsing of DHCP option 6rd, which is used for IPv6 tunneling configuration. When the udhcpc client encounters a maliciously crafted DHCP server response containing oversized or malformed OPTION_6RD data, it fails to properly validate the buffer boundaries before copying data into heap-allocated memory regions. This results in a classic heap overflow condition where adjacent memory locations become overwritten, potentially leading to arbitrary code execution, system instability, or denial of service conditions. The vulnerability falls under CWE-121 heap-based buffer overflow, which is categorized as a fundamental memory safety issue.
From an operational perspective, this vulnerability poses significant risks to network infrastructure and connected devices that rely on BusyBox-based DHCP clients for network configuration. Attackers can exploit this flaw by positioning themselves as malicious DHCP servers on the network, sending specially crafted responses to vulnerable clients. The impact of exploitation can range from complete system compromise to persistent denial of service conditions, particularly affecting embedded devices, routers, and IoT appliances that commonly utilize BusyBox implementations. The vulnerability is particularly concerning in environments where devices automatically connect to unknown networks or where network access controls are insufficient.
Security practitioners should prioritize immediate patching of all affected BusyBox installations to version 1.25.0 or later, which includes proper bounds checking and input validation for DHCP option parsing. Network segmentation and DHCP server authentication mechanisms can serve as temporary mitigations while patches are deployed. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation may enable attackers to execute arbitrary code on compromised devices. Additionally, implementing network monitoring for unusual DHCP traffic patterns and conducting regular vulnerability assessments of embedded network devices can help detect potential exploitation attempts. Organizations should also consider implementing DHCP snooping and dynamic ARP inspection to limit the effectiveness of man-in-the-middle attacks that could leverage this vulnerability.