CVE-2019-9924 : Exploit Details and Defense Strategies

In pre-4.4-beta2 versions of Bash, rbash did not include safeguards to restrict modifications to BASH_CMDS by the shell user, allowing the user to execute any command with the privileges of the shell.

Understanding CVE-2019-9924

In this CVE, a vulnerability in Bash before version 4.4-beta2 enabled users to modify BASH_CMDS, potentially leading to unauthorized command execution.

What is CVE-2019-9924?

CVE-2019-9924 is a security vulnerability in Bash versions prior to 4.4-beta2 that allowed users to manipulate BASH_CMDS, granting them the ability to run commands with the shell's permissions.

The Impact of CVE-2019-9924

The vulnerability could be exploited by malicious users to execute arbitrary commands with the privileges of the shell, potentially leading to unauthorized access and system compromise.

Technical Details of CVE-2019-9924

This section provides detailed technical information about the CVE.

Vulnerability Description

In Bash versions before 4.4-beta2, rbash did not prevent users from altering BASH_CMDS, enabling them to execute commands with the shell's permissions.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions: Pre-4.4-beta2 versions of Bash

Exploitation Mechanism

The vulnerability allowed shell users to modify BASH_CMDS, granting them the ability to execute commands with the privileges of the shell.

Mitigation and Prevention

Protect your systems from CVE-2019-9924 with these mitigation strategies.

Immediate Steps to Take

Update Bash to version 4.4-beta2 or newer to mitigate the vulnerability.
Monitor system logs for any suspicious activities that could indicate exploitation.

Long-Term Security Practices

Implement the principle of least privilege to restrict user capabilities.
Regularly audit and review user permissions to prevent unauthorized access.

Patching and Updates

Apply security patches promptly to ensure that known vulnerabilities are addressed.