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In cybersecurity, even small misconfigurations can lead to significant vulnerabilities. One such example is an exposed Exchange Web Services (EWS) endpoint, which can leak critical information like:
– Microsoft Exchange version
– Internal hostname
– Authentication methods (NTLM, Basic Auth)
Attackers can exploit this for internal reconnaissance, brute-force attacks, or NTLM relay attacks.
You Should Know:
1. Identifying Exposed EWS Endpoints
Use tools like Nmap or curl to check for exposed EWS endpoints:
nmap -p 443 --script http-title <target-ip> curl -v https://<target-ip>/ews/
Look for responses revealing Exchange version or authentication methods.
2. Analyzing Server Responses
If the server responds with excessive details, it may be misconfigured:
curl -I https://<target-ip>/ews/
Check for headers like:
– `X-OWA-Version` (Exchange version)
– `WWW-Authenticate: NTLM` (NTLM authentication enabled)
3. Exploiting NTLM Relay Attacks
If NTLM authentication is enabled, attackers can relay credentials:
python3 ntlmrelayx.py -t ldap://<DC-IP> -smb2support
This can lead to domain compromise if not mitigated.
4. Mitigation Steps for Admins
- Disable Basic Auth & NTLM in Exchange:
Set-OrganizationConfig -OAuth2ClientProfileEnabled $true
- Restrict EWS access to trusted IPs.
- Update Exchange to the latest version.
What Undercode Say:
Exposed EWS endpoints are a goldmine for attackers, providing critical intel for further exploitation. Security researchers must:
– Document findings ethically and report them responsibly.
– Use tools like Nmap, Responder, and Metasploit for testing.
– Stay updated with Exchange Server patches.
Key Commands to Remember:
Check for open EWS ports: nmap -p 443,80,25 <target-ip> Test NTLM authentication: crackmapexec smb <target-ip> -u '' -p '' --ntlm Disable legacy auth (PowerShell): Set-CasMailbox -Identity [email protected] -EWSEnabled $false
Prediction:
As cloud adoption grows, misconfigured Exchange servers will remain a prime target for attackers. Expect more NTLM relay and brute-force attacks in 2025, pushing organizations to enforce Zero Trust policies.
Expected Output:
A detailed report on exposed EWS vulnerabilities, exploitation techniques, and mitigation steps.
References:
Reported By: Vivek Goswami – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
