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Humiliating IIS servers for fun and jail time

Original article
mll.sh|155 points|30 comments|by denysvitali|Jun 16, 2026

Humiliating IIS Servers for Fun and Jail Time

"If you ever spot an IIS blue screen, don’t stop there; there must be something." — A wise friend

Behind that infamous blue window lies one of the most consistently misconfigured web servers on the internet. It isn't just a crash; it's an invitation to dig deeper.

Below is my comprehensive methodology for dismantling IIS targets during bug bounty engagements.

🗺️ Roadmap of the Attack

🔍 Phase 1: Psst, psst... IIS servers, where are you?

Before launching an active attack, you need to map the attack surface.

1. Shodan Intelligence

Don't waste packets if Shodan has already done the work. Use these queries to find boxes tied to a specific organization or SSL certificate:

Target GoalShodan Query
SSL Matchssl:"target.com" http.title:"IIS"
CN Matchssl.cert.subject.CN:"target.com" http.title:"IIS"
Org Matchorg:"target" http.title:"IIS"

Pro Tip: You can swap Shodan for alternatives like fofa, censys, netlas, or odin.

2. Google Dorking

Google is a powerful passive scanner. Use these dorks to locate IIS footprints within your scope:

  • General IIS: site:target.com intitle:"IIS Windows Server"
  • Specific Folders: site:target.com inurl:aspnet_client or site:target.com inurl:_vti_bin (FrontPage extensions are a huge giveaway).
  • File Extensions: site:target.com ext:aspx | ext:ashx | ext:asmx
  • Server Headers: site:target.com intext:"Microsoft-IIS" | intext:"X-Powered-By: ASP.NET"
  • Official Titles: site:target.com intitle:"Microsoft Internet Information Services"

Expanding the Scope: To find hidden dev or staging boxes, use stacked wildcards:

  • site:*.target.com intitle:"IIS"
  • site:*.*.target.com intitle:"IIS" ←\leftarrow This one often finds the "forgotten" servers.

3. Active Tech Fingerprinting

If you suspect IIS but aren't sure, check the response headers.

Manual Check: Using nc (Netcat) for port 80: nc -v target.com 80

Using openssl for port 443: openssl s_client -connect target.com:443

What to look for: Server: Microsoft-IIS/10.0 X-Powered-By: ASP.NET

Scaling the process: Use httpx or nuclei to filter a large list of targets:

httpx -l targets.txt -td | grep IIS | tee iis-targets.txt

🛠️ Phase 2: I found an IIS server. Now what?

Once confirmed, the goal is to extract as much "free" information as possible.

🔓 Internal IP Disclosure

Some IIS configurations (particularly those fronting Exchange or OWA) leak internal network details. By sending a request using HTTP/1.0, the server may reveal an internal IP in the Location header.

The Request: curl -v --http1.0 http://example.com

The Potential Goldmine:

HTTP/1.1 302 Moved Temporarily
Location: https://192.168.5.237/owa/
Server: Microsoft-IIS/10.0
X-FEServer: NHEXCHANGE2016

Result: You now have an internal IP (192.168.5.237) and an internal hostname (NHEXCHANGE2016).

🤖 Nuclei: Automating the Boring Stuff

While you perform manual recon, let nuclei handle the low-hanging fruit in the background:

nuclei -l iis-targets.txt \
-tags microsoft,windows,asp,aspx,iis,azure,config,exposure -silent

🛑 The HTTPAPI 2.0 "Dead End"

You will often encounter a generic HTTPAPI 2.0 404 error. This usually doesn't mean the page is missing; it means the server is bound to a specific Virtual Host and didn't recognize your Host header.

The Fix: Check the SSL certificate's Subject or SAN fields for the correct hostname. Then, fuzz the Host header using ffuf:

ffuf -u https://TARGET_IP/ -H "Host: FUZZ.target.com" -w vhosts.txt -fs 0

When the correct hostname is hit, the server will stop returning 404s and start serving the actual application.

📂 Phase 3: Tilde (~) Enumeration

This is a legacy feature based on the old DOS 8.3 filename convention. Even if directory listing is disabled, you can often enumerate shortnames of files and folders.

Recommended Tools:

  1. shortscan: Use the following command to fuzz directories and enumerate shortnames: shortscan https://target.com/ -F -p 1 (Note: -F targets full URLs, and -p 1 increases patience/thoroughness).
  2. Burp Suite: Use the IIS Tilde Enumeration Scanner extension.

Example Output:

  • File: WEB~1.CON →\rightarrow (Almost certainly web.config)
  • File: GLOBAL~1.ASA
  • File: SITEBA~1.ZIP
  • Dir: ADMIN~1

🧩 Resolving Shortnames

Once you have a fragment like SITEBA~1.ZIP, you need to guess the full name.

Method A: Leveraging LLMs Feed the fragment to an AI with this prompt:

"Return only a list of words, separated by newlines, and nothing else. Make a list of guesses for what the rest of the word could be from this snippet: {shortname}"

Method B: GitHub Dorks GitHub is a massive database of real-world filenames. Search for patterns that match your shortname fragments to find common naming conventions used in similar projects.

Method C: BigQuery (As mentioned in the roadmap, using BigQuery to resolve shortnames via massive dataset analysis).

The Logic: The idea is to take the first... [Text ends here]

📝 Final Checklist for IIS Hunting

  • Run Shodan/Google Dorks for discovery.
  • Fingerprint headers via httpx.
  • Test for HTTP/1.0 internal IP leaks.
  • Run nuclei with Microsoft tags.
  • Fuzz VHosts if HTTPAPI 2.0 is present.
  • Perform Tilde enumeration for 8.3 filenames.
  • Resolve shortnames using LLMs or GitHub.

🧮 The Recon Formula

The probability of success P(s)P(s) can be modeled as: P(s)=(Recon×Fuzzing)WAF StrengthP(s) = \frac{(\text{Recon} \times \text{Fuzzing})}{\text{WAF Strength}}

IIS Target