🚨 Breaking O-Auth: 4 Days Challenge 🚨
Are you ready to put your cybersecurity skills to the test? Join us in the Breaking O-Auth: 4 Days Challenge by @Mebledy and dive deep into the world of OAuth! Over the next four days, you'll explore, exploit, and defend against real-world vulnerabilities in one of the most critical authorization frameworks on the web.
🔐 What’s in store?
- Day 1: Learn the basics and set up your vulnerable OAuth environment.
- Day 2: Identify and exploit common OAuth vulnerabilities.
- Day 3: Master advanced attack vectors and bypass techniques.
- Day 4: Secure OAuth and implement strong defense strategies.
This challenge is perfect for security enthusiasts, penetration testers, and developers looking to level up their web security game. Whether you're just starting out or a seasoned pro, there’s something here for everyone.
💥 Ready to take on the challenge? Join us and showcase your skills!
#CyberSecurity #OAuth #PenetrationTesting #InfoSec #WebSecurity #ChallengeAccepted #TechCommunity #LearningJourney #HackingChallenge #EthicalHacking #SecureCode
🔗 https://nas.io/brutsecurity/challenges/breaking-oauth-4-days-challenge
Are you ready to put your cybersecurity skills to the test? Join us in the Breaking O-Auth: 4 Days Challenge by @Mebledy and dive deep into the world of OAuth! Over the next four days, you'll explore, exploit, and defend against real-world vulnerabilities in one of the most critical authorization frameworks on the web.
🔐 What’s in store?
- Day 1: Learn the basics and set up your vulnerable OAuth environment.
- Day 2: Identify and exploit common OAuth vulnerabilities.
- Day 3: Master advanced attack vectors and bypass techniques.
- Day 4: Secure OAuth and implement strong defense strategies.
This challenge is perfect for security enthusiasts, penetration testers, and developers looking to level up their web security game. Whether you're just starting out or a seasoned pro, there’s something here for everyone.
💥 Ready to take on the challenge? Join us and showcase your skills!
#CyberSecurity #OAuth #PenetrationTesting #InfoSec #WebSecurity #ChallengeAccepted #TechCommunity #LearningJourney #HackingChallenge #EthicalHacking #SecureCode
🔗 https://nas.io/brutsecurity/challenges/breaking-oauth-4-days-challenge
nas.io
Breaking O-Auth : 4 Days Challenge
4 days • Challenge by Rahim7x
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🪲 Bug Bounty Pro Tip: #H2C Upgrade Bypass
Target: Applications using HTTP/2 Cleartext (h2c) upgrades.
The Core Idea: Many Web Application Firewalls (WAFs) and reverse proxies process HTTP/1.1 but fail to correctly inspect traffic after it's upgraded to HTTP/2.
How to Test:
1. Find a target that accepts an Upgrade: h2c header (common in Java, gRPC, and some reverse proxies like Nginx).
2. Send an initial HTTP/1.1 request with the upgrade header:
3. If the server agrees (responds with HTTP/1.1 101 Switching Protocols), the connection is now HTTP/2.
4. The Bypass: Craft and send malformed or smuggled HTTP/2 frames (e.g., with the :method header set to GET or POST). The downstream WAF may not parse this, allowing you to access internal endpoints or bypass security controls.
Why it works: The security boundary often only exists at the HTTP/1.1 layer. Once upgraded, your HTTP/2 traffic might be forwarded directly to the backend without inspection.
#BugBounty #Hacking #WebSecurity #WAFBypass #HTTP2
Target: Applications using HTTP/2 Cleartext (h2c) upgrades.
The Core Idea: Many Web Application Firewalls (WAFs) and reverse proxies process HTTP/1.1 but fail to correctly inspect traffic after it's upgraded to HTTP/2.
How to Test:
1. Find a target that accepts an Upgrade: h2c header (common in Java, gRPC, and some reverse proxies like Nginx).
2. Send an initial HTTP/1.1 request with the upgrade header:
GET / HTTP/1.1
Host: example.com
Upgrade: h2c
Connection: Upgrade
3. If the server agrees (responds with HTTP/1.1 101 Switching Protocols), the connection is now HTTP/2.
4. The Bypass: Craft and send malformed or smuggled HTTP/2 frames (e.g., with the :method header set to GET or POST). The downstream WAF may not parse this, allowing you to access internal endpoints or bypass security controls.
Why it works: The security boundary often only exists at the HTTP/1.1 layer. Once upgraded, your HTTP/2 traffic might be forwarded directly to the backend without inspection.
#BugBounty #Hacking #WebSecurity #WAFBypass #HTTP2
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♾Bug Bounty Tip: Bypassing WAFs for Stored XSS via ASCII-Hex Encoded PDF Payloads
➡️Many platforms allow users to upload PDFs that get previewed/rendered directly in the browser (often using libraries like PDF.js in Firefox, Chrome extensions, embedded viewers, or custom implementations).
A clever trick for Stored XSS (or Blind XSS variants):
1. Craft a classic XSS payload (e.g., one that executes alert(document.domain) or exfiltrates cookies/tokens).
2. Encode the entire malicious JavaScript as ASCII hex (each character → \xHH format).
3. Embed it inside a tiny/valid PDF structure that triggers execution during font/glyph rendering or object parsing in vulnerable PDF renderers.
4. Upload the PDF to a target feature that stores and previews user-uploaded documents (profile, reports, tickets, resumes, invoices, shared files, etc.).
5. When a victim (admin, user, or support) previews/opens the PDF in a vulnerable renderer → XSS fires in the context of the PDF viewer.
⚡️Key advantages:
- Many WAFs / upload filters / content scanners completely miss it because it's not a classic <script> or HTML — it's binary-ish PDF content with hex-encoded JS.
- Can be tuned for Stored → persistent until deleted.
- Can be adapted for Blind XSS → exfiltrate to your server instead of alert().
💬Real-world notes from hunters:
- Works especially well against PDF.js-based previews (Firefox default, many web apps embed it).
- Reference: Similar to behavior seen in CVE-2024-4367 (arbitrary JS exec in PDF.js via font handling path).
- Impact varies:
- Self-XSS / low-priv user alert → usually P4–P5 or Informational.
- Admin views it → potential session theft / higher severity (P2–P3 possible if you can prove escalation).
- Some programs reject pure alert() PoCs in sandboxed viewers (no cookie access in most cases) → demonstrate real impact (e.g., redirect, keylogger, token exfil) or target-specific quirks.
- Pro tip: Test on your primary programs that have PDF preview/generation features — many still do!
⚡️Resources to start:
- Repo with example payloads: https://github.com/orwagodfather/XSS-Payloads
- Edit payloads easily in Notepad++ (hex view or find/replace).
Happy hunting — stay ethical & report responsibly! 🏆
Photo Credit- Orwa
#bugbountytip #bugbounty #xss #websecurity #pdfxss
➡️Many platforms allow users to upload PDFs that get previewed/rendered directly in the browser (often using libraries like PDF.js in Firefox, Chrome extensions, embedded viewers, or custom implementations).
A clever trick for Stored XSS (or Blind XSS variants):
1. Craft a classic XSS payload (e.g., one that executes alert(document.domain) or exfiltrates cookies/tokens).
2. Encode the entire malicious JavaScript as ASCII hex (each character → \xHH format).
3. Embed it inside a tiny/valid PDF structure that triggers execution during font/glyph rendering or object parsing in vulnerable PDF renderers.
4. Upload the PDF to a target feature that stores and previews user-uploaded documents (profile, reports, tickets, resumes, invoices, shared files, etc.).
5. When a victim (admin, user, or support) previews/opens the PDF in a vulnerable renderer → XSS fires in the context of the PDF viewer.
⚡️Key advantages:
- Many WAFs / upload filters / content scanners completely miss it because it's not a classic <script> or HTML — it's binary-ish PDF content with hex-encoded JS.
- Can be tuned for Stored → persistent until deleted.
- Can be adapted for Blind XSS → exfiltrate to your server instead of alert().
💬Real-world notes from hunters:
- Works especially well against PDF.js-based previews (Firefox default, many web apps embed it).
- Reference: Similar to behavior seen in CVE-2024-4367 (arbitrary JS exec in PDF.js via font handling path).
- Impact varies:
- Self-XSS / low-priv user alert → usually P4–P5 or Informational.
- Admin views it → potential session theft / higher severity (P2–P3 possible if you can prove escalation).
- Some programs reject pure alert() PoCs in sandboxed viewers (no cookie access in most cases) → demonstrate real impact (e.g., redirect, keylogger, token exfil) or target-specific quirks.
- Pro tip: Test on your primary programs that have PDF preview/generation features — many still do!
⚡️Resources to start:
- Repo with example payloads: https://github.com/orwagodfather/XSS-Payloads
- Edit payloads easily in Notepad++ (hex view or find/replace).
Happy hunting — stay ethical & report responsibly! 🏆
Photo Credit- Orwa
#bugbountytip #bugbounty #xss #websecurity #pdfxss
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🛡️ Bug Bounty Tip: Test IDOR + Web Cache Deception Together
When hunting IDORs, always check for web cache deception on the same endpoints:
1. As User A, access a sensitive resource like
2. As User B, repeat the exact same URL with identical headers.
3. Only change the Cookie/Auth token.
If User B receives User A's 200 OK response from cache → you've likely found a critical vulnerability!
This combo can lead to account takeover-level impacts.
#BugBounty #AppSec #WebSecurity #IDOR #Pentesting
When hunting IDORs, always check for web cache deception on the same endpoints:
1. As User A, access a sensitive resource like
/api/invoices/123 (also try appending .css or `.js`).2. As User B, repeat the exact same URL with identical headers.
3. Only change the Cookie/Auth token.
If User B receives User A's 200 OK response from cache → you've likely found a critical vulnerability!
This combo can lead to account takeover-level impacts.
#BugBounty #AppSec #WebSecurity #IDOR #Pentesting
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🚨Bug Bounty Tip: Test Newline Injection in JSON Parameters
When testing API endpoints, don’t assume parameters like
For password-reset functionality, try newline injection:
If the backend fails to properly validate or sanitize the parameter, it may interpret both email addresses as separate recipients and send the password-reset link to both accounts.
This can indicate a parameter parsing / input validation flaw and, depending on the application logic and impact, potentially lead to account-related security issues.
Things to test:
•
• Multiple values in the same parameter
• JSON arrays vs. strings
• Duplicate JSON keys
• URL-encoded newline characters
• Different API content types
Always test only on systems you’re authorized to assess.
#BugBounty #BugBountyTips #API #APISecurity #WebSecurity #Pentesting #CyberSecurity
When testing API endpoints, don’t assume parameters like
email accept only a single value.For password-reset functionality, try newline injection:
{
"action": "reset-password",
"email": "accA@mail.com\naccB@mail.com"
}If the backend fails to properly validate or sanitize the parameter, it may interpret both email addresses as separate recipients and send the password-reset link to both accounts.
This can indicate a parameter parsing / input validation flaw and, depending on the application logic and impact, potentially lead to account-related security issues.
Things to test:
•
\n and \r\n separators• Multiple values in the same parameter
• JSON arrays vs. strings
• Duplicate JSON keys
• URL-encoded newline characters
• Different API content types
Always test only on systems you’re authorized to assess.
#BugBounty #BugBountyTips #API #APISecurity #WebSecurity #Pentesting #CyberSecurity
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Don’t only test Unicode domains. Test Unicode in email/username fields too.
Try lookalike characters such as:
a → á / other Unicode variantsThe interesting case is when:
Database: treats the values as equal
Application: identifies the victim account
SMTP: treats them as different addresses
Example:
victim@gmail.comvictim@gmáil.comIf the application finds the victim's account but sends the password-reset email to the attacker-controlled Unicode address, you may have an account-collision / account-takeover vulnerability.
Input → Validation → Database → Token generation → Email delivery
#BugBounty #IDNHomograph #Punycode #WebSecurity
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