21. Web Application Testing Tools
21.2 Burp Suite: Proxy and Intercept
In short: Burp Suite (Community Edition, free, ships with Kali) is the most-used web testing tool.
Burp Suite (Community Edition, free, ships with Kali) is the most-used web testing tool. Setup:
- Start Burp:
burpsuite(or from the Kali menu). Use the temporary project. - Proxy, Options: the proxy listens on
127.0.0.1:8080by default. - In Firefox, set the network proxy to
127.0.0.1:8080(the FoxyProxy add-on makes this one click). - Install Burp's CA certificate: browse to
http://burp, download the cert, and add it in Firefox so HTTPS sites work without warnings. - Proxy, Intercept: turn Intercept on, browse to DVWA, and watch requests stop in Burp.
Main Burp tabs:
| Tab | What it does |
|---|---|
| Proxy | Intercept and view every request/response |
| Target, Site map | A tree of everything you have browsed |
| Repeater | Send one request again and again, editing it each time |
| Intruder | Automate many requests with changing values (rate-limited in Community) |
| Decoder | Encode/decode URL, Base64, HTML |
| Comparer | Diff two responses |
Repeater is where you will spend most time: right-click a request, "Send to Repeater", change one value, hit Send, read the response. This is how you test one input at a time.
Ravindra Bagale's Tip
Students leave "Intercept is on" and forget it, then say "the internet isn't working" – because every request is held in Burp. When you don't need it, keep Intercept off; the site map and history still keep filling up. This is the number one confusion every beginner goes through.
Ravindra Bagale's Tip – मराठी
"Intercept is on" ठेवून students विसरतात, आणि मग "internet चालत नाही" म्हणतात – कारण प्रत्येक request Burp मध्ये थांबलेली असते. काम नसेल तेव्हा Intercept off ठेवा; site map आणि history तरीही भरत राहतात. हा number one confusion सगळे नवशिके अनुभवतात.
Ravindra Bagale's Tip – हिंदी
"Intercept is on" छोड़कर students भूल जाते हैं, और फिर कहते हैं "internet नहीं चल रहा" – क्योंकि हर request Burp में रुकी होती है. जब काम न हो तब Intercept off रखो; site map और history फिर भी भरते रहते हैं. यह number one confusion हर नया सीखने वाला झेलता है.
Lab
Set up Burp with Firefox and the CA certificate. Log in to DVWA through Burp, find the login request in the HTTP history, send it to Repeater, change the username, and observe the different response. Take a screenshot of the request and response side by side.
Extended teaching notes
Why this lesson matters
Kali tools are dual-use. In this course every run ends with a defensive note: what config would have blocked or detected the activity on a system you own.
Rule
Host-only lab, written scope, no bridging onto real LANs.
Mini case study
Suppose we are on a purple-team exercise for an Indian mid-size company (sample data). Red notes a technique from this lesson against a lab clone. Blue must show the control that stops it, the log that would have fired, and the ticket that hardens production. That is the standard this course trains you for.
Defender's worksheet (do this today)
- Write the lesson title, date and the exact lab target you are allowed to use.
- List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
- Run one safe check from the lesson on a lab system only. Paste the command and output.
- Write a two-sentence fix you would give a teammate.
- Name one related public advisory (CERT-In, CISA, NVD, or a vendor bulletin) with its date.
Indian workplace (sample data)
Suppose we are a junior analyst at Infosys, TCS, Wipro or a fintech SOC in Bengaluru/Pune. Turn this lesson into one checklist item with an owner, a due date and a place to store evidence (ticket + screenshot).
Global practice
Compare your notes with OWASP, CIS Benchmarks, NIST CSF/IR guidance or a cloud Well-Architected security question. Write five lines on what overlaps.
Everyday analogy
Explain the risk and the fix to a family member without jargon. If they can repeat the warning, you understand it well enough to teach juniors.
Key terms
- Control: a safeguard (patch, config, process, detection).
- Finding: a weakness backed by evidence.
- Remediation: the fix plus how you verified it.
- Scope: systems you have written permission to touch.
- Least privilege: only the access the task needs.
- Defence in depth: several layers so one failure does not end the story.
Common mistakes
- Skipping written permission "just for a quick scan".
- Practising on hostel, office or public targets without authorisation.
- Collecting tool output without writing the fix.
- Copying attack steps onto production to "verify". Defenders verify with versions, configs and patches.
- Publishing screenshots that contain secrets, cookies or internal hostnames.
Recap
- Evidence, fix, owner, date.
- Own lab only.
- Fix > spectacle.