CVE-2000-0585 in DHCP Client
Summary
by MITRE
ISC DHCP client program dhclient allows remote attackers to execute arbitrary commands via shell metacharacters.
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Analysis
by VulDB Data Team • 02/13/2017
The CVE-2000-0585 vulnerability represents a critical security flaw in the ISC DHCP client program dhclient that enables remote attackers to execute arbitrary commands through the exploitation of shell metacharacters. This vulnerability specifically targets the command line argument processing mechanism within the dhclient utility, which is widely deployed across unix and linux systems for dynamic host configuration protocol client operations. The flaw arises from insufficient input validation and sanitization when processing network configuration parameters received from dhcp servers, creating a pathway for malicious actors to inject and execute unauthorized commands on affected systems.
The technical implementation of this vulnerability stems from the improper handling of user-supplied data within the dhclient process. When the dhcp client receives configuration parameters from a malicious dhcp server, it fails to properly escape or validate special shell characters such as semicolons, ampersands, or backticks that could be used to chain commands. This allows an attacker positioned on the same network segment or capable of man-in-the-middle attacks to craft specially formatted dhcp responses that, when processed by the vulnerable dhclient, result in arbitrary command execution with the privileges of the dhclient process. The vulnerability is particularly dangerous because it can be exploited without requiring authentication or direct system access, making it an attractive target for network-based attacks.
The operational impact of CVE-2000-0585 extends beyond simple command execution to potentially compromise entire network infrastructures. An attacker exploiting this vulnerability could gain unauthorized access to affected systems, install backdoors, modify network configurations, or escalate privileges to root access depending on the execution context. The vulnerability affects systems running the ISC DHCP client software, which was widely adopted across enterprise and organizational networks, potentially exposing thousands of systems to remote code execution attacks. This makes the vulnerability particularly concerning for network administrators who may not be aware of the extent of dhclient installations across their infrastructure.
Security professionals should consider this vulnerability in the context of broader network attack frameworks such as those described in the mitre ATT&CK framework where it maps to command and control techniques involving remote code execution and privilege escalation. The vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in shell commands, a common pattern in command injection attacks. Organizations should implement immediate mitigations including network segmentation to prevent unauthorized dhcp server access, deployment of dhcp snooping mechanisms, and application of vendor patches to the ISC DHCP client software. Additionally, system administrators should consider implementing monitoring for unusual dhclient behavior and regularly audit dhcp server configurations to ensure only trusted servers can respond to client requests. The vulnerability underscores the importance of input validation in network protocols and highlights the critical need for secure coding practices in network management utilities.