RedHat和CentOS的bash漏洞修复
RedHat和CentOS 检查bash漏洞方法，如果显示下面提示，说明存在漏洞
# env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
vulnerable
this is a test
具体修补方法，不用指定bash版本，因为系统自己会识别的
yum update bash -y /sbin/ldconfig rpm -qa bash
打完补丁后，下面示例
centos 5.5系统
# rpm -qa bash bash-3.2-33.el5.1
centos 6.4系统
# rpm -qa bash bash-4.1.2-15.el6_5.1.x86_64
打完补丁后执行,如果是下面的提示，说明漏洞已经修复
# 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
RedHat漏洞说明 https://access.redhat.com/articles/1200223
漏洞的危害 https://securityblog.redhat.com/2014/09/24/bash-specially-crafted-environment-variables-code-injection-attack/
RedHat修复方式 https://securityblog.redhat.com/2014/09/24/bash-specially-crafted-environment-variables-code-injection-attack/
CentOS修复方式 http://lists.centos.org/pipermail/centos/2014-September/146099.html
不过现在网上有另一种说法，即使打补丁，不过还可以绕过去，那么
如果php-fpm用www用户运行的话，需要检查/etc/passwd 下是不是可以登录的/bin/bash
www:x:80:80::/home/www:/bin/bash
如果是，那么需要执行
# chsh www -s /sbin/nologin Changing shell for www. Shell changed.
现在php-fpm的用户www为www:x:80:80::/home/www:/sbin/nologin，可以阻止用此用户登录到后台
如果没有进行上面的更新升级，可以进行如下做一步到位的补丁修复，直接将bash更新为bash-4.1.2-15.el6_5.2.X86_64(CentOS6系列)：
再次升级为bash-4.1.2-15.el6_5.2.x86_64
由于昨天打的补丁还可以绕过去，所以今天再次升级，这次升级的版本为
bash-4.1.2-15.el6_5.2.x86_64（CentOS 6）
https://rhn.redhat.com/errata/RHSA-2014-1306.html# Red Hat Enterprise Linux Server (v. 6)
# yum update bash Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: mirrors.skyshe.cn * extras: mirrors.skyshe.cn * updates: mirrors.skyshe.cn Setting up Update Process Resolving Dependencies --> Running transaction check ---> Package bash.x86_64 0:4.1.2-15.el6_5.1 will be updated ---> Package bash.x86_64 0:4.1.2-15.el6_5.2 will be an update --> Finished Dependency Resolution Dependencies Resolved ===================================================================================== Package Arch Version Repository Size ===================================================================================== Updating: bash x86_64 4.1.2-15.el6_5.2 updates 905 k Transaction Summary ===================================================================================== Upgrade 1 Package(s) Total download size: 905 k Is this ok [y/N]: y Downloading Packages: bash-4.1.2-15.el6_5.2.x86_64.rpm | 905 kB 01:22 Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Updating : bash-4.1.2-15.el6_5.2.x86_64 1/2 Cleanup : bash-4.1.2-15.el6_5.1.x86_64 2/2 Verifying : bash-4.1.2-15.el6_5.2.x86_64 1/2 Verifying : bash-4.1.2-15.el6_5.1.x86_64 2/2 Updated: bash.x86_64 0:4.1.2-15.el6_5.2 Complete!
如果显示的版本依然是bash-4.1.2-15.el6_5.1.x86_64，那么清空yum缓存后再更新，至此，漏洞修复完善，可以安心
# yum clean all
# yum makecache #这两步一般不用
# yum update bash
# /sbin/ldconfig
# rpm -qa bash
bash-4.1.2-15.el6_5.2.x86_64
# env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
this is a test #现在说明漏洞已修复
