CVE-1999-1407 in Linux
Summary
by MITRE
ifdhcpc-done script for configuring dhcp on red hat linux 5 allows local users to append text to arbitrary files via a symlink attack on the dhcplog file.
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Analysis
by VulDB Data Team • 10/20/2024
The vulnerability described in CVE-1999-1407 represents a classic symlink attack scenario that exploits insecure file handling practices within the network configuration scripts of Red Hat Linux 5. This issue specifically targets the ifdhcpc-done script which is responsible for configuring dhcp settings on affected systems. The flaw arises from the script's improper handling of temporary files during the dhcp configuration process, creating an opportunity for local attackers to manipulate system files through symbolic link manipulation.
The technical implementation of this vulnerability stems from the script's failure to properly validate or secure the dhcplog file path before writing to it. When the ifdhcpc-done script executes, it creates or appends to a dhcplog file without sufficient checks to prevent symlink attacks. An attacker can create a symbolic link with the name dhcplog that points to any target file on the system, then trigger the script execution. This allows the attacker to append arbitrary content to files that they would normally not have write access to, effectively bypassing normal file permissions and access controls. The vulnerability is categorized under CWE-59 as an issue with improper handling of symbolic links, specifically in the context of temporary file creation and manipulation.
The operational impact of this vulnerability is significant for local attackers who can leverage it to escalate their privileges or corrupt system files. By appending content to critical system files such as configuration files, log files, or even binary files, attackers can potentially cause system instability, data corruption, or create backdoor access points. The attack vector is particularly dangerous because it requires minimal privileges and can be executed by any local user. This type of vulnerability aligns with ATT&CK technique T1059.007 for execution through command and script interpreters, where local users can manipulate system processes to achieve unauthorized access. The vulnerability also relates to T1548.001 for privilege escalation through the exploitation of insecure file operations.
Mitigation strategies for this vulnerability involve multiple approaches that address both the immediate security flaw and broader system hardening practices. The most direct solution is to modify the ifdhcpc-done script to properly handle temporary files by using secure file creation methods such as creating files with restrictive permissions and ensuring proper file path validation. System administrators should implement proper file permission controls and regularly audit network configuration scripts for similar vulnerabilities. The use of secure temporary file creation functions and avoiding predictable file names can prevent symlink attacks. Additionally, implementing proper access controls and monitoring for unauthorized file modifications can help detect exploitation attempts. This vulnerability highlights the importance of following secure coding practices and the principle of least privilege in system administration, as outlined in various security frameworks and standards that emphasize the need for robust file handling procedures in system scripts.