The Shellshock vulnerability (CVE-2014-6271) allows attackers to execute arbitrary commands via crafted environment variables in Bash. In this example, the malicious command cat /etc/passwd is executed, displaying the contents of the file (which contains system user account info).

Reference – CEH v13 Official Study Guide:

Module 6: Malware Threats

Quote:

“Shellshock allows remote code execution through environment variables processed by Bash. Exploits can be used to run commands like cat /etc/passwd on a vulnerable system.”

Incorrect Options:

A. No file deletion occurs.

B. It doesn’t change passwords.

C. No user addition occurs.

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