Top 50 Interview Questions & Answers | Penetration Testing

Penetration Testing, legal form of hacking, where a security expert uses all set of tools to break a system with permission of the owner of IT system. Here, in this article, I will discuss Top 50 Interview Questions and Answers.

Q1. What is Information Security?

Ans: In simple words, Information Security is a practice to secure information from any unauthorized access. ISO/IEC 27000:2009 defined this term as “Preservation of confidentiality, integrity, and availability of information. Note: In addition, other properties, such as authenticity, accountability, non-repudiation, and reliability can also be involved.”

Q2. What is the importance of A Penetration Test?

Ans: Penetration Testing is important for identification of vulnerabilities in an IT system from outside the network. Generally, It is an activity done after vulnerability assessment. In simple words you can say, by doing Penetration testing, security analyst attempting to gain access to resources without knowledge of usernames, passwords and other normal means of access. You can only differentiate hacker from security expert is the permission given by the organization.


Q3. What are the phases of Network Penetration?

Ans: Penetration testing dividing into 5 phases:
Phase 1 – Reconnaissance It is a process of collecting data about the target. It can be performed actively or passively. In this phase, you learn more and more about target business and its operation. Activities include identifying the target, finding out the target IP address range, network, domain name, mail server, DNS records, etc.
Phase 2 – Scanning This is another crucial phase of penetration testing. In this phase, scanning has been done to identify vulnerabilities in the network and also software and OS used by devices. After this activity, pen tester knows about services running, open ports, firewall detection, vulnerabilities, OS etc. There are a lot of tools available both open source and paid.
Phase 3 – Gaining Access In this phase, pen tester started execution of attack by gaining access to vulnerable devices and servers. This can be done by using tools.  
Phase 4 – Maintaining Access As en tester already gained access to a vulnerable system, in this phase he/she try to extract as much data and also remain stealthy.
Phase 5 – Covering Tracks In this phase, pen tester takes all the necessary steps to hide the intrusion and possible controls left behind for future visits. He/she also remove all kinds of logs, uploaded backdoor(s) and anything related to the attack.

Q4. What is XSS or Cross Site Scripting?

Ans:  As explained by OWASP, “Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted websites. XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.”

Q5. What is the difference between asymmetric and symmetric encryption?

Ans: The major difference between symmetric and asymmetric cryptography is the use of the single key for encryption and decryption in case of symmetric cryptography while the use of the public and private key for encryption and decryption in case of asymmetric cryptography.

Q6. What is “Vulnerability”?

Ans: The vulnerability is a term which every information security expert want to eradicate from IT system. If someone exploited those vulnerabilities, may result in an intentional or unintentional compromise of a system.

Q7. Discuss a recent project of pen test which you have done?

Ans: To answer this question, you can start with the last project which you have done in the field of a pen test. Also mention about your approach, which tools you have used, which vulnerabilities you have found and how you help the developer to fix those issues.

Q8. What are the strengths and differences between Windows and Linux?


PriceAvailable FreePaid
Ease Of UseLittle difficult for beginnersUser-friendly
Reliabilitymore reliable and secureless reliable and secure
less reliable and secureavailable for install both paid and freesoftware available for install both paid and free
Software Costmost software available for freemostly commercial software available
HardwareIn beginning, hardware compatibility was an issue. But now, the majority of physical appliance support LinuxHardware compatibility never an issue for Windows
SecurityHighly secure Operating SystemAs this OS used by the novice user, it is vulnerable to hackers
SupportCommunity support available online for rectifying any issueMicrosoft support available online and also many books published to diagnosed any issue.
Use CasesUsed mainly by corporate, scientific and educational instituteUsed mainly by novice users, gamers, corporates etc. where more skills are not required

Q9. What kind of penetration can be done with the Diffie Hellman exchange?

Ans:  Diffie–Hellman key exchange (DH) is a method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols.
Weak ephemeral Diffie-Hellman parameter detection for SSL/TLS services is a kind of PT can be done with this method.

Q10. What type of tools are there out there for packet sniffing?

Ans:  Packet Sniffing is a process of capture network traffic and able to see traffic on an entire network or only a certain segment of it with the help of packet sniffing tool, depending on how the network switches are configured, placed, etc. Most popular packet sniffing tool available free is Wireshark.

Q11. How will you protect the data during and after Penetration Testing?

Ans: Pen Tester clearly specified policy regarding the finding of user data while testing. The policy tells what to do if any data encountered during and after testing. Although Backup is must to avoid any loss of data.

Q12. What is the Intrusion Detection?

Ans: Intrusion Detection, as the name suggests, it protects IT infrastructure from any cyber attack.  It identifies security breaches from both outsides and within a network. Intrusion Detection performs a wide variety of functions which include monitoring and analyzing of traffic, recognize the pattern of attack, check the integrity of file reside in servers, check if any policy violation happens etc.

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Disclaimer: This tutorial is for educational purpose only. Individual is solely responsible for any illegal act.


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