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Updated post at https://ishaqmohammed.me/posts/application-security-engineer-interview-questions/

Application Security Engineer Interview Questions

Some of the questions/topics which i was asked when i was giving interviews for Application/Product Security Engineering roles. I am sure this is not an exhaustive list but i felt these questions were important to be asked and some were challenging to answer. I tried to include the reference resource for some of the questions/topics, feel free to reach out to me on twitter for any feedback/suggestions/discussions.

• Which architecture is more secure? 2 tier or 3 tier

• Explain SSL Handshake

  • https://www.youtube.com/watch?v=ubHZQrECeew

  • https://www.cloudflare.com/learning/ssl/how-does-ssl-work/

  • https://www.cloudflare.com/learning/ssl/what-happens-in-a-tls-handshake/

• Recommend XXE mitigation for application which requires external entities to be called because of business requirement

• Explain CORS and SOP

  • https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS

  • https://portswigger.net/web-security/cors

  • https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy

  • https://www.bedefended.com/papers/cors-security-guide

• Does SOP mitigate CSRF attacks?

  • https://security.stackexchange.com/questions/157061/how-does-csrf-correlate-with-same-origin-policy

• Exploiting SSRF attacks

  • https://portswigger.net/web-security/ssrf

  • https://www.hackerone.com/blog-How-To-Server-Side-Request-Forgery-SSRF

  • https://blog.appsecco.com/an-ssrf-privileged-aws-keys-and-the-capital-one-breach-4c3c2cded3af

• What is web cache deception?

  • https://blog.cloudflare.com/understanding-our-cache-and-the-web-cache-deception-attack/

  • http://omergil.blogspot.com/2017/02/web-cache-deception-attack.html

  • https://portswigger.net/research/practical-web-cache-poisoning

• What is HTTP request smuggling?

  • http://projects.webappsec.org/w/page/13246928/HTTP%20Request%20Smuggling

  • https://portswigger.net/web-security/request-smuggling

• Explain DOM XSS. Can DOM XSS be stored? Can CSP header mitigate dom based XSS

  • https://www.html5rocks.com/en/tutorials/internals/howbrowserswork/

  • https://html.spec.whatwg.org/multipage/parsing.html

  • https://portswigger.net/web-security/cross-site-scripting/dom-based

  • https://brutelogic.com.br/blog/dom-based-xss-the-3-sinks/

  • https://www.scip.ch/en/?labs.20171214

• What will be your testcase for a file upload functionality?

  • https://medium.com/@satboy.fb/art-of-unrestricted-file-upload-exploitation-92ed28796d0

  • https://resources.infosecinstitute.com/file-upload-vulnerabilities/#gref

  • https://pentestlab.blog/2012/11/19/abusing-file-upload/

  • https://pentestlab.blog/2012/11/29/bypassing-file-upload-restrictions/

• What is HSTS?

  • https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Strict-Transport-Security

• Explain SSL Stripping

  • https://blog.cloudflare.com/performing-preventing-ssl-stripping-a-plain-english-primer/

• If you have API calls which need to fetch credentials, what will be the secure way to store secrets and making them available for API calls?

  • https://medium.com/hackernoon/where-do-you-keep-credentials-for-your-lambda-functions-cac746048480

• How does file compression work?

• Which method is secure? Compress First and then Encrypt the data or Encrypt First then Compress

• You have found a vulnerability a product/infrastructure, how will you investigate if this was not exploited already by an attacker

• What is SPF, DKIM and DMARC?

  • https://www.smartertools.com/blog/2019/04/09-understanding-spf-dkim-dmarc

  • https://www.endpoint.com/blog/2014/04/15/spf-dkim-and-dmarc-brief-explanation

  • https://www.reddit.com/r/sysadmin/comments/aph6ee/lets_talk_about_email_spoofing_and_prevention_alt/

• Explain DNS Exfiltration

• Explain Log Poisoning using LFI/RFI

  • https://www.hackingarticles.in/apache-log-poisoning-through-lfi/

  • https://www.hackingarticles.in/rce-with-lfi-and-ssh-log-poisoning/

  • https://highon.coffee/blog/lfi-cheat-sheet/

• Do the HttpOnly cookie and X-XSS-Protection header mitigate cross-site scripting attacks?

• How do you exploit XSS in a post request?

  • https://portswigger.net/blog/exploiting-xss-in-post-requests

• Difference: IDOR, Missing function level access control and privilege escalation

• How does burp suite work with HTTPs requests?

  • https://www.quora.com/How-is-it-possible-that-a-proxy-tool-like-Burp-Suite-is-able-to-decrypt-HTTPS-communication-like-plain-text-credentials

  • https://portswigger.net/burp/documentation/desktop/tools/proxy/using

• Is the DNS service's communication encrypted?

• Security implications in DNS

• DNS over HTTPs

  • https://hacks.mozilla.org/2018/05/a-cartoon-intro-to-dns-over-https/

  • https://www.chromium.org/developers/dns-over-https

• How does ssh authentication work?

  • https://www.digitalocean.com/community/tutorials/understanding-the-ssh-encryption-and-connection-process

  • https://gravitational.com/blog/ssh-handshake-explained/

• How to create and implement an SSL certificate?

• How to verify if a database is encrypted?

• If you want a script to use credentials from the system, where will you store the credentials?

• Explain SDLC

• In which phase of SDLC should security be integrated?

• Explain encryption in Wifi network communication.

• What are stateless and stateful requests?

  • https://www.geeksforgeeks.org/difference-between-stateless-and-stateful-protocol/

• How is the state of a request saved in HTTP?

• What data does the shadow file contains?

  • https://www.cyberciti.biz/faq/understanding-etcshadow-file/

• What is salt in cryptography?

• What is Double-Submit Cookie?

• What is Preflight request?

  • https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request

• What are Certificate Transparency Logs?

• What is your favourite vulnerability and why?

• Talk about any latest/interesting vulnerability or breach you learnt about.

Further readings and references:

• Resources-for-Application-Security

• How to prepare for a security engineer interview by Eray Mitrani

• Security_Engineer_Interview_Questions by Tad Whitaker

• Security Engineer - Interview Questions by Namish

• 60 Cybersecurity Interview Questions 2019 Update by Daniel Miessler