使用Ansible和apt，如何为可远程攻击的安全漏洞CVE-2014-6271更新bash？

Question

给定bash的远程代码执行漏洞于2014年9月24日宣布，如何使用Ansible更新基于apt的系统？

Answer 1

这里是我最喜欢的解决方案，在一个相当均匀的环境中。这样做的好处是，与其他人使用的version=latest模式不同，将来更新不会花费太多时间。

- name: update apt cache if not done today
  apt: update_cache=yes cache_valid_time=86400

# http://seclists.org/oss-sec/2014/q3/650
- name: ensure secure ansible, ubuntu 1204 edition
  apt: pkg=bash=4.2-2ubuntu2.5 state=present
  when: ansible_distribution=='Ubuntu' and ansible_distribution_version=='12.04'

- name: ensure secure ansible, ubuntu 1404 edition
  apt: pkg=bash=4.3-7ubuntu1.3 state=present
  when: ansible_distribution=='Ubuntu' and ansible_distribution_version=='14.04'

# based on the following gist and comments below. there have been several exploits, this covers them well.
# https://gist.github.com/kacy/2b9408af04c71fab686e
- name: ensure bash is not vulnerable to 201409 problem
  shell: "foo='() { echo not patched; }' bash -c foo"
  register: command_result
  ignore_errors: yes
  failed_when: "'command not found' not in command_result.stderr"

说明:如果每天更新很多次的话，更新apt缓存是很昂贵的。可以调整缓存时间。代码实际上是测试以确保漏洞是固定的-测试是好的。这将突出显示任何未被编码的发行版/版本所涵盖的主机。

用户@jarv 发布了一个很好的解决方案也是如此。而不是总是更新apt，它只在问题没有得到解决的情况下才这样做。这是最快的解决方案(至少在这个答案中)。jarv也有在链接回购中添加了分发测试。，对于异构环境很有用。

- name: Check if we are vulnerable
  shell: executable=/bin/bash env x='() { :;}; echo vulnerable'  bash -c "echo this is a test"
  register: test_vuln

- name: Apply bash security update if we are vulnerable
  apt: name=bash state=latest update_cache=true
  when: "'vulnerable' in test_vuln.stdout"

- name: Check again and fail if we are still vulnerable
  shell: executable=/bin/bash env x='() { :;}; echo vulnerable'  bash -c "echo this is a test"
  when: "'vulnerable' in test_vuln.stdout"
  register: test_vuln
  failed_when: "'vulnerable' in test_vuln.stdout"

还有其他的方法。Ansible的创建者Michael DeHaan和官方@ansible账户在推特上发布了几个解决方案：

这是一条单线

ansible all -m apt -a 'update_cache=yes name=bash state=latest'

这里有一个更新和检查的解决方案

- name: update apt
  command: apt-get update

- name: update bash
  command: apt-get --only-upgrade install bash

- name: check bash fix
  command: env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
  register: command_result
  failed_when: "'error' not in command_result.stderr"