Linux security Vulnerability Bash patching method

Bash how to deal with the problem of security vulnerability

One: Vulnerability description

The vulnerability stems from the special environment variables created before the bash shell that you invoke, which can contain code and be executed by bash.

II: Software and systems identified for successful use

All Linux operating systems that install the version of Gun bash are less than or equal to 4.3.

Three: Vulnerability detection method

[Email protected] ~]# bash-version
GNU Bash, version 4.1.2 (1)-release (X86_64-REDHAT-LINUX-GNU)
Copyright (C) Software Foundation, Inc.
License gplv3+: GNU GPL version 3 or later

This was free software; Redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Input:

[[email protected] ~]# env x= ' () {:;}; Echo vulnerable ' bash-c "echo this is a test"

Output:

Vulnerable

This is a test

If the above information appears, the system has a vulnerability.

Four: Treatment methods

Here are the actions on the virtual machine

[[email protected] ~]# yum-y Update bash

After you upgrade bash, perform the test:

[[email protected] ~]# env x= ' () {:;}; Echo vulnerable ' bash-c "echo this is a test"

BASH:WARNING:X: Ignoring function definition attempt

Bash:error importing function definition for ' x '

This is a test

If shown above, indicates that the vulnerability has been patched.

Linux security Vulnerability Bash patching method