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Introduction:
In the high-stakes world of bug bounty hunting, scope definition is everything. When a target restricts you to staging.example.com, many hunters immediately start scanning subdomains or fuzzing directories. However, a more sophisticated approach leverages external intelligence gathering. By querying public archives like VirusTotal, hunters can uncover historical data associated with a domain, often revealing leaked credentials, exposed API keys, and live authentication tokens that were inadvertently stored there by third-party services, turning a standard recon phase into a high-severity finding.
Learning Objectives:
- Understand how to leverage VirusTotal’s passive DNS and file search capabilities for bug bounty recon.
- Learn to extract and validate leaked authentication tokens and API keys from public datasets.
- Master the process of responsibly reporting discovered credentials to ensure they are accepted as in-scope vulnerabilities.
You Should Know:
1. The VirusTotal Recon Methodology: Unearthing Hidden Tokens
VirusTotal is primarily known as a malware analysis tool, but its backend stores years of submitted files and URLs. When a domain like `staging.example.com` is in scope, you can search VirusTotal for any file, PCAP, or URL that contacted that host. Often, developers or automated systems submit samples containing configuration files, log dumps, or HAR (HTTP Archive) files that inadvertently include session tokens, Bearer tokens, or Basic Auth strings.
– Step‑by‑step guide:
1. Navigate to the VirusTotal website and use the search query: domain:staging.example.com.
2. Navigate to the “Relations” tab and review the “Historic SSL Certificates” and “Passive DNS Replicas” to understand the infrastructure.
3. Go back to the main search and use: `staging.example.com` to view all submitted URLs. Look for any URL paths containing log, debug, env, or backup.
4. Utilize the “Search” function for files. Use the query: metadata:staging.example.com. This will list files submitted to VT that contain the domain string. Download any suspicious .env, .json, or `.log` files for offline inspection.
2. Extracting and Validating Live Auth Tokens
Once you have downloaded files from the VirusTotal archive, the manual inspection process begins. In the example referenced, the hunter found 9 live auth tokens. These are often found in HAR files exported from browsers (which contain session cookies and headers) or in Android/iOS application dumps.
– Step‑by‑step guide:
1. Linux Command Line (Grep): If you have a directory of downloaded files, use `grep` to hunt for authorization patterns.
grep -r -E "Authorization: Bearer [A-Za-z0-9-_]+|api[<em>-]?key[[:space:]][:=][[:space:]]['\"]?[A-Za-z0-9]+|token[:=][[:space:]]['\"]?[A-Za-z0-9-</em>]+" ./vt_downloads/
2. Validate the Token: Do not just report the token blindly. Use `curl` to test if the token is still active against the staging environment. Note: Ensure your testing does not cause damage or data alteration.
curl -H "Authorization: Bearer <EXTRACTED_TOKEN>" https://staging.example.com/api/v1/user/profile
3. If the endpoint returns user data or a `200 OK` instead of a 401 Unauthorized, you have confirmed a live, valid credential.
3. Windows Command Line Hunting
For hunters operating in a Windows environment, PowerShell offers robust tools for sifting through downloaded threat data.
– Step‑by‑step guide:
1. Open PowerShell and navigate to the directory containing your VirusTotal downloads.
2. Use `Select-String` to find authentication patterns (similar to grep).
Get-ChildItem -Recurse -File | Select-String -Pattern "(Authorization: Bearer|api_key|auth_token)" | group path | select name
3. To view the context of the found tokens, pipe the results to Format-List.
Get-ChildItem -Recurse -File | Select-String -Pattern "(eyJ[A-Za-z0-9-_]+.eyJ[A-Za-z0-9-_]+.[A-Za-z0-9-_]+)" Regex for JWT tokens
4. Expanding the Hunt: Beyond VirusTotal
While VirusTotal is a primary source, this methodology extends to other public sandboxes and code repositories.
– Configuration:
– Hybrid-Analysis: Search for the domain. Look for “Extracted Strings” and “Network Communications” sections in reports. These often contain cleartext HTTP requests with headers.
– Any.Run: Review public submissions that interacted with your target domain. Check the “TCP/UDP” flows for captured credentials.
– GitHub Dorks: Combine the domain name with dorks like `filename:.env` or `Authorization` in GitHub searches. Credentials hardcoded in public repos are a common entry point.
5. Responsible Disclosure and Impact Amplification
When you find these tokens, simply reporting “I found a token” often results in a low severity or a “Informative” rating. You must demonstrate impact.
– Step‑by‑step guide:
1. Identify the Service: Determine what the token accesses (e.g., AWS, a database admin panel, a user data API).
2. Demonstrate Access: Take a redacted screenshot showing the data you can access. If the token provides admin-level API access, show a list of users or server configurations.
3. Write the Report: State clearly: “Using OSINT techniques on VirusTotal, I discovered a historical file submission containing an active Bearer token for staging.example.com. This token currently grants access to [bash] endpoints, exposing PII/internal data.”
4. As noted in the comments, be prepared to provide the “impact statement” immediately. Do not just hand over the token keys without context.
What Undercode Say:
- Key Takeaway 1: Public sandboxes are the new “robots.txt” for bug hunters. They are the most overlooked source of sensitive data leakage because developers forget that their debugging sessions are often uploaded automatically to security scanners.
- Key Takeaway 2: Automation is key. Relying on manual searches for “Authorization” strings is inefficient. Hunters should script the downloading of PCAPs and files associated with their target domains from multiple APIs to run regular credential leakage checks.
The analysis here highlights a shift in reconnaissance: moving from active scanning (which can be noisy and detected) to passive intelligence mining. By sifting through the digital exhaust left by other applications and services, a penetration tester can bypass authentication mechanisms entirely. This method proves that your application is only as secure as the third-party services that interact with it. If a Slack bot, a CI/CD pipeline, or a malware sandbox leaks your staging credentials, your perimeter has already been breached.
Prediction:
As AI-powered code analysis tools become more prevalent, we will see a rise in automated “Credential Leakage as a Service” for bug hunters. AI agents will be trained to scrape VirusTotal, PublicWWW, and GitHub on an hourly basis, correlating found tokens with live endpoints to automatically validate them. This will force security teams to implement “Credential Cycling” policies where tokens are rotated daily rather than quarterly, and to adopt “Leak-Proof” authentication methods like device authorization grants that are useless outside their intended context.
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Reported By: 0xbartita Bugbountytips – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
