CVE-1999-1407 is a vulnerability found in the ifdhcpc-done script used for configuring DHCP on Red Hat Linux version 5.0. This script is responsible for handling DHCP client configuration tasks, including logging DHCP events to a file named dhcplog. The vulnerability arises because the script does not properly handle symbolic links (symlinks) when writing to the dhcplog file. A local attacker with access to the system can create a symlink named dhcplog pointing to an arbitrary file on the filesystem. When the ifdhcpc-done script runs, it appends text to the target of the symlink, effectively allowing the attacker to append arbitrary data to any file they can link to. This can lead to unauthorized modification of files, potentially altering system configurations or scripts. The attack requires local access, no authentication is needed, and the exploit complexity is low since it only involves creating a symlink before the script execution. The vulnerability does not impact confidentiality or availability but affects integrity by allowing unauthorized file modifications. There is no patch available for this vulnerability, and no known exploits have been reported in the wild. The CVSS score is low (2.1), reflecting the limited scope and impact of the vulnerability.

For European organizations, the impact of this vulnerability is generally low due to its requirement for local access and the limited scope of affected systems (Red Hat Linux 5.0, an outdated and unsupported version). However, if legacy systems running this version are still in use, the vulnerability could allow an insider or local attacker to modify critical configuration files or scripts, potentially leading to privilege escalation or persistence mechanisms. This could disrupt operations or compromise system integrity. Given that many European organizations have moved to more recent Linux distributions, the direct risk is minimal. Nonetheless, organizations with legacy infrastructure or specialized industrial systems running old Red Hat Linux versions should be cautious. The vulnerability could also be leveraged in multi-user environments where untrusted users share access, such as in academic or research institutions.

Since no official patch is available, European organizations should consider the following specific mitigation steps: 1) Upgrade or migrate systems from Red Hat Linux 5.0 to a supported and updated Linux distribution to eliminate the vulnerability entirely. 2) Restrict local access to trusted users only, minimizing the risk of symlink attacks by unprivileged users. 3) Implement filesystem permissions and mount options that prevent users from creating symlinks in directories where the ifdhcpc-done script writes logs. 4) Monitor and audit the dhcplog file and other critical system files for unauthorized modifications. 5) Use mandatory access control systems (e.g., SELinux or AppArmor) to limit the ifdhcpc-done script’s ability to write outside intended files. 6) If upgrading is not immediately possible, consider replacing or modifying the ifdhcpc-done script to safely handle symlinks or disable DHCP client scripts that are vulnerable.