CVE-2018-1122 in procps-ng
Summary
by MITRE
procps-ng before version 3.3.15 is vulnerable to a local privilege escalation in top. If a user runs top with HOME unset in an attacker-controlled directory, the attacker could achieve privilege escalation by exploiting one of several vulnerabilities in the config_file() function.
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability identified as CVE-2018-1122 affects procps-ng versions prior to 3.3.15 and represents a significant local privilege escalation flaw within the top command utility. This vulnerability exploits a critical weakness in how the system handles configuration file processing when the HOME environment variable is not properly set. The issue arises from the improper handling of file paths and permissions during the configuration file parsing process, creating a dangerous condition where unprivileged users can manipulate system resources to gain elevated privileges. The vulnerability specifically targets the config_file() function which lacks proper validation of file access and modification operations.
The technical exploitation of this vulnerability occurs when a user executes the top command with an unset HOME environment variable while operating from a directory controlled by an attacker. This condition allows the attacker to manipulate the configuration file loading sequence and inject malicious content that gets executed with elevated privileges. The flaw stems from insufficient input validation and improper file path resolution mechanisms within the application's configuration handling code. The vulnerability can be classified under CWE-22 as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" and CWE-78 as "Improper Neutralization of Special Elements used in OS Command Injection." The attack vector leverages the principle of least privilege violation by allowing a user to escalate their privileges through manipulation of application configuration files.
From an operational perspective, this vulnerability poses a severe risk to system security as it enables local users to gain root privileges without requiring authentication or complex exploitation techniques. The impact extends beyond simple privilege escalation to potentially allow full system compromise, as the elevated privileges could be used to modify system files, install backdoors, or access sensitive data. The vulnerability is particularly dangerous because it requires minimal user interaction and can be exploited from any directory where an attacker has write access. Security professionals should note that this vulnerability aligns with ATT&CK technique T1068 "Exploitation for Privilege Escalation" and T1548.001 "Abuse Elevation Control Mechanism" within the MITRE ATT&CK framework. The vulnerability demonstrates how seemingly innocuous command-line utilities can become attack vectors when proper security controls are not implemented.
Mitigation strategies for CVE-2018-1122 include immediate patching of procps-ng to version 3.3.15 or later, which contains the necessary fixes for the configuration file handling vulnerabilities. System administrators should also implement proper environment variable validation and ensure that the HOME environment variable is always properly set for all users. Additional protective measures include restricting write permissions on directories where top might be executed, implementing mandatory access controls, and monitoring for suspicious configuration file modifications. The vulnerability highlights the importance of secure coding practices in system utilities and the need for proper input validation and privilege separation mechanisms. Organizations should conduct comprehensive vulnerability assessments to identify other potentially affected applications and ensure that all system utilities are running patched versions to prevent similar exploitation scenarios.