Automount daemon automountd allows local or remote users to gain privileges via shell metacharacters.
Automountd, a critical component of Unix-like systems, is vulnerable to a privilege escalation attack. This vulnerability allows attackers to execute arbitrary commands with elevated privileges, potentially leading to complete system compromise. Successful exploitation grants attackers unauthorized access to sensitive data and control over the affected system.
Step 1: Target Identification: The attacker identifies a system running a vulnerable version of automountd.
Step 2: Payload Crafting: The attacker crafts a malicious payload containing shell metacharacters to execute arbitrary commands. This payload is designed to be injected into a mount point or other configuration parameter.
Step 3: Payload Delivery: The attacker attempts to trigger the vulnerability by sending a crafted mount request, typically through the mount command or by manipulating the automount configuration files.
Step 4: Command Injection: The automountd daemon processes the mount request, failing to properly sanitize the attacker-supplied input. The shell metacharacters within the payload are interpreted by the shell.
Step 5: Privilege Escalation: The injected commands are executed with the privileges of the automountd daemon (usually root), granting the attacker elevated access.
Step 6: System Compromise: The attacker leverages the elevated privileges to gain unauthorized access, modify system files, install backdoors, or exfiltrate sensitive data.
The vulnerability stems from insufficient input validation within the automountd daemon when handling mount requests. Specifically, the daemon fails to properly sanitize shell metacharacters (e.g., ;, |, &, $) present in the mount point or other configuration parameters. This allows an attacker to inject malicious commands into the automount configuration, which are then executed with the privileges of the automountd process, typically root. The root cause is a lack of proper input sanitization and command injection prevention, leading to arbitrary command execution.