CVE-2016-2147 in BusyBox
Summary
by MITRE
Integer overflow in the DHCP client (udhcpc) in BusyBox before 1.25.0 allows remote attackers to cause a denial of service (crash) via a malformed RFC1035-encoded domain name, which triggers an out-of-bounds heap write.
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Analysis
by VulDB Data Team • 11/12/2022
The vulnerability identified as CVE-2016-2147 represents a critical integer overflow flaw within the DHCP client implementation of BusyBox, specifically affecting versions prior to 1.25.0. This issue resides in the udhcpc component which is commonly deployed in embedded systems and network appliances that rely on BusyBox for essential Unix utilities. The vulnerability manifests when the DHCP client processes malformed RFC1035-encoded domain names, creating a condition where integer arithmetic operations exceed their valid range and result in unpredictable behavior.
The technical root cause of this vulnerability stems from improper input validation and boundary checking within the domain name parsing logic. When processing network responses containing malformed domain names, the DHCP client performs integer calculations to determine buffer sizes and memory allocation requirements. An attacker can craft a specially formatted RFC1035 domain name that causes these integer values to overflow, leading to an out-of-bounds heap write operation. This type of vulnerability falls under CWE-190, which specifically addresses integer overflow conditions that can result in memory corruption.
The operational impact of CVE-2016-2147 is significant as it enables remote attackers to execute denial of service attacks against systems running vulnerable versions of BusyBox. The vulnerability can be exploited through network-based attacks where an attacker controls a DHCP server or intercepts network traffic to deliver maliciously crafted domain names. Upon exploitation, the out-of-bounds heap write corrupts memory structures, typically resulting in application crashes and system instability. This affects a wide range of embedded devices including routers, IoT appliances, network switches, and other network infrastructure equipment that utilize BusyBox as their core system utilities framework.
Systems utilizing vulnerable versions of BusyBox are particularly at risk in environments where DHCP servers may be compromised or when attackers can influence network traffic through man-in-the-middle attacks. The vulnerability demonstrates the importance of proper input validation and bounds checking in network protocol implementations, as highlighted by ATT&CK technique T1059.3.005 for command and scripting interpreter. Organizations should prioritize patching their systems to upgrade to BusyBox version 1.25.0 or later, which includes fixes for this integer overflow condition. Additionally, network segmentation and monitoring can help detect anomalous DHCP traffic patterns that might indicate exploitation attempts, while implementing proper DHCP server authentication mechanisms can reduce the attack surface for such vulnerabilities.