EC-Council
312-50V11 · Question #653
312-50V11 Question #653: Real Exam Question with Answer & Explanation
The correct answer is D: The attacker is attempting an exploit that launches a command-line shell. The presence of 0x90 NOP instructions (a NOP sled) combined with '/bin/sh' in the payload strongly indicates a shellcode-based buffer overflow attack designed to spawn a Unix shell.
System Hacking
Question
The following is an entry captured by a network IDS.You are assigned the task of analyzing this entry. You notice the value 0x90, which is the most common NOOP instruction for the Intel processor. You figure that the attacker is attempting a buffer overflow attack. You also notice "/bin/sh" in the ASCII part of the output. As an analyst what would you conclude about the attack?
Exhibit
Options
- AThe buffer overflow attack has been neutralized by the IDS
- BThe attacker is creating a directory on the compromised machine
- CThe attacker is attempting a buffer overflow attack and has succeeded
- DThe attacker is attempting an exploit that launches a command-line shell
Explanation
The presence of 0x90 NOP instructions (a NOP sled) combined with '/bin/sh' in the payload strongly indicates a shellcode-based buffer overflow attack designed to spawn a Unix shell.
Common mistakes.
- A. An IDS captures and alerts on traffic but does not inherently block or neutralize attacks - that is the role of an IPS or firewall.
- B. The '/bin/sh' string references the shell binary, not a directory creation operation such as mkdir.
- C. The IDS capture shows an attempt in progress; success cannot be confirmed from network traffic alone without observing the target system's response and state.
Concept tested. NOP sled and shellcode identification in buffer overflow
Reference. https://owasp.org/www-community/attacks/Buffer_overflow_attack
Topics
#buffer overflow#NOP sled#shellcode#exploit analysis
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