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Introduction:
In the high-stakes world of bug bounty hunting, a “Duplicate” or “N/A” response isn’t a failure—it’s a data point. As highlighted by Prashant Sengar’s February recap, the path to securing bounties is paved with reports that don’t pay out. This article dissects the methodology behind transforming those “wasted” submissions into a streamlined, effective vulnerability discovery process. We will explore the technical reconnaissance, validation steps, and reporting nuances that separate sporadic luck from consistent, high-impact findings.
Learning Objectives:
- Understand how to analyze “Duplicate” and “N/A” reports to refine future recon and exploitation techniques.
- Learn to implement a standardized methodology for target reconnaissance using CLI tools.
- Master the art of crafting Proof of Concept (PoC) reports that minimize the chance of dismissal.
You Should Know:
- Reconnaissance: The Art of Finding What Others Miss
The reason many reports get flagged as “Duplicate” is simple: the low-hanging fruit has already been picked. To find unique vulnerabilities, you must dig deeper than the average scanner.
Step‑by‑step guide for deep recon:
Instead of just browsing the main domain, we will use a combination of automated tools and manual checks to expand the attack surface.
Linux Commands:
1. Subdomain Enumeration using Assetfinder and Amass assetfinder -subs-only target.com | tee subs.txt amass enum -passive -d target.com | tee -a subs.txt <ol> <li>Probing for live hosts and web servers cat subs.txt | httprobe -c 50 -t 3000 | tee live-subs.txt</p></li> <li><p>Crawling the live hosts to find hidden endpoints cat live-subs.txt | waybackurls | tee wayback-data.txt cat live-subs.txt | gau --subs | tee gau-data.txt</p></li> <li><p>Filtering for specific parameter-based endpoints (potential XSS/SQLi) cat wayback-data.txt | grep "=" | uro | tee potential-params.txt
Explanation: These commands build a map of the target’s digital infrastructure. `Assetfinder` and `Amass` gather subdomains that are often forgotten. `httprobe` filters for live websites. `waybackurls` and `gau` (GetAllUrls) fetch historical URLs, which may contain deprecated parameters or endpoints that are vulnerable but no longer linked on the main site. The final `grep` isolates URLs containing parameters (=), which are prime real estate for injection attacks.
2. Handling “N/A” Responses: Validating the Attack Surface
An “N/A” (Not Applicable) often means the vulnerability exists, but it is out of scope or the impact is negligible. To avoid this, you must validate the business logic before writing the report.
Step‑by‑step guide for scope validation:
Windows Command (using PowerShell):
Fetch and parse the scope of a target from a bug bounty platform (Example using curl) curl -s https://bugbountyplatform.com/programs/target-scope | Select-String -Pattern "target.com"
Linux Command (using curl and jq):
Assuming the scope is in a JSON format curl -s https://api.bugbountyplatform.com/scopes/target.com | jq '.data.in_scope[]'
Explanation: Before firing off an exploit, cross-reference your findings with the official scope. If you find a subdomain hosting a development server (dev.target.com) running an outdated Apache version, but the scope explicitly excludes .dev.target.com, your report is automatically N/A. Documenting that the asset is in scope is the first step of your PoC.
3. Differentiating Depth from Duplicates
When you receive a duplicate notification, analyze the triager’s notes. Usually, they point to the original report. Use this intel to find a variant they missed.
Step‑by‑step guide for variant analysis:
If the original report identified an XSS in the `search` parameter, but the fix only filtered specific characters, you can bypass it.
1. Identify the vulnerable endpoint: `https://target.com/search?q=test`
2. Test the original payload: `` (This should now be blocked).
3. Craft a bypass payload (using ASCII encoding or alternative tags):
– Try: `”>`
– Try encoding: `%3Cscript%3Ealert(1)%3C/script%3E` (If the WAF decodes URL encoding before sanitizing, this might slip through).
4. Check for Context: If the parameter is reflected inside a JavaScript variable, break out of the string:
– Payload: `’;alert(1);//`
Explanation: This is how you turn a duplicate into a valid finding. You are attacking the patch, not the original vulnerability. This requires manual testing that automated scanners rarely perform.
4. API Security: Finding the Hidden Endpoints
Modern web apps rely heavily on APIs. These are goldmines for bug hunters as they often expose direct object references (IDOR) or lack rate limiting.
Step‑by‑step guide for API enumeration:
Linux Command (using ffuf for fuzzing):
Fuzz for common API endpoints on a discovered subdomain ffuf -w /usr/share/wordlists/api_endpoints.txt -u https://api.target.com/FUZZ -fc 403,404 Check for Swagger/OpenAPI documentation (often left exposed) ffuf -w endpoints.txt -u https://target.com/FUZZ -w .txt -fc 404
Common wordlist entries: swagger.json, swagger-ui.html, v1, v2, graphql, internal, docs.
Explanation: If you find https://api.target.com/v1/users/1234`, try changing the `1234` to5678`. If the API returns data for another user without requiring additional authorization, you have found an IDOR (Insecure Direct Object Reference)—a highly bountiful vulnerability.
5. Cloud Hardening: The Misconfiguration Hunt
Many modern vulnerabilities are not in the code, but in the configuration of cloud storage (AWS S3, Azure Blob).
Step‑by‑step guide for S3 bucket enumeration:
Linux Commands:
1. Use a tool like 's3scanner' to check for buckets s3scanner --bucket target-backup --dump <ol> <li>If the bucket is public, list the contents aws s3 ls s3://target-backup/ --no-sign-request --region us-east-1</p></li> <li><p>Download interesting files for further analysis (config files, backups) aws s3 cp s3://target-backup/backup.zip . --no-sign-request
Explanation: Developers often leave backup buckets open to the public. `s3scanner` checks the existence and permissions of buckets. Using the `–no-sign-request` flag in the AWS CLI attempts to access the bucket without credentials. If it works, the bucket is wide open, potentially exposing source code or database dumps.
6. Exploitation and Mitigation: SQL Injection Deep Dive
SQLi remains a staple finding, but deep exploitation requires precision to avoid damaging the database.
Step‑by‑step guide for boolean-based blind SQLi:
- Identify the injection point: `https://target.com/product?id=5`
2. Test for vulnerability:
– Payload: `https://target.com/product?id=5 AND 1=1` (Page loads normally)
– Payload: `https://target.com/product?id=5 AND 1=2` (Page loads blank/error)
– Result: If the behavior differs, it is vulnerable to Boolean-based Blind SQLi.
3. Extract Database Name (Manual enumeration using Burp Suite Intruder):
– Payload: `id=5 AND (SELECT ascii(substring(database(),1,1))) > 64`
– Iterate through characters until you reconstruct the name.
4. Mitigation Code Snippet (Node.js – Prepared Statement):
// Vulnerable Code
// connection.query('SELECT FROM products WHERE id = ' + req.params.id, ...)
// Mitigated Code (Parameterized Query)
connection.query('SELECT FROM products WHERE id = ?', [req.params.id], ...)
Explanation: The manual extraction shows the depth required for a valid report. The mitigation code snippet is crucial when writing the report; including remediation advice increases your credibility and the bounty reward.
7. The Final Report: Turning Findings into Bounties
A valid finding with a poor report often gets downgraded. Structure your submission like a professional penetration testing deliverable.
Template for a High-Impact Report:
- [Vulnerability Type] in [bash] leading to [bash] (e.g., IDOR in `api/v3/user/details` leading to Mass Data Exposure).
- Summary: One-liner explaining the flaw.
- Steps to Reproduce:
1. Log in as user `[email protected]`.
- Intercept the request to `https://api.target.com/v3/user/details`.
- Change the `user_id` parameter from `1000` to
1001. - Observe that the response returns the PII of user
1001.
– Impact: An attacker can enumerate all user IDs and scrape the entire user database, leading to a massive data breach and violation of GDPR/CCPA compliance.
– Proof of Concept (PoC): A screenshot or video showing the request/response.
– Remediation: Implement proper authorization checks. The endpoint should verify that the `user_id` in the request matches the session token of the logged-in user.
What Undercode Say:
- Methodology Over Tools: Prashant’s experience highlights that while tools find the noise, methodology finds the signal. The ability to pivot from a “Duplicate” to a new attack vector is a skill developed through rigorous, documented process, not by running the latest scanner.
- The Value of “N/A”: In cybersecurity, knowing what not to chase is as important as knowing what to exploit. The validation process forced by N/A responses builds a mental model of the target’s architecture, making your future attacks more surgical and effective.
Prediction:
As AI-powered code review tools become standard in DevOps pipelines, the low-hanging fruit (simple XSS, basic SQLi) will nearly disappear. The bug bounty landscape will shift entirely towards business logic flaws, AI prompt injections, and complex cloud misconfigurations. The hunters who survive will be those who, like Prashant, treat every duplicate as a lesson in logic, not just a lesson in code. The era of automated spraying is over; the era of manual, logical exploitation has just begun.
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IT/Security Reporter URL:
Reported By: Prashant Sengar – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
