External Reconnaissance

IP Space

Valid ASN for our target, netblocks in use for the organization's public-facing infrastructure, cloud presence and the hosting providers, DNS record entries, etc.

Domain Information

Based on IP data, DNS, and site registrations. Who administers the domain? Are there any subdomains tied to our target? Are there any publicly accessible domain services present? (Mailservers, DNS, Websites, VPN portals, etc.) Can we determine what kind of defenses are in place? (SIEM, AV, IPS/IDS in use, etc.)

Schema Format

Can we discover the organization's email accounts, AD usernames, and even password policies? Anything that will give us information we can use to build a valid username list to test external-facing services for password spraying, credential stuffing, brute forcing, etc.

Data Disclosures

For data disclosures we will be looking for publicly accessible files ( .pdf, .ppt, .docx, .xlsx, etc. ) for any information that helps shed light on the target. For example, any published files that contain intranet site listings, user metadata, shares, or other critical software or hardware in the environment (credentials pushed to a public GitHub repo, the internal AD username format in the metadata of a PDF, for example.)

Breach Data

Any publicly released usernames, passwords, or other critical information that can help an attacker gain a foothold.

We (HTB) have addressed the why and what of external reconnaissance; let's dive into the where and how.

ASN / IP registrars

IANA, arin for searching the Americas, RIPE for searching in Europe, BGP Toolkit

Domain Registrars & DNS

Domaintools, PTRArchive, ICANN, manual DNS record requests against the domain in question or against well known DNS servers, such as 8.8.8.8.

Social Media

Searching Linkedin, Twitter, Facebook, your region's major social media sites, news articles, and any relevant info you can find about the organization.

Public-Facing Company Websites

Often, the public website for a corporation will have relevant info embedded. News articles, embedded documents, and the "About Us" and "Contact Us" pages can also be gold mines.

Cloud & Dev Storage Spaces

Breach Data Sources

HaveIBeenPwned to determine if any corporate email accounts appear in public breach data, Dehashed to search for corporate emails with cleartext passwords or hashes we can try to crack offline. We can then try these passwords against any exposed login portals (Citrix, RDS, OWA, 0365, VPN, VMware Horizon, custom applications, etc.) that may use AD authentication.

Hunting For Files

filetype:pdf inurl:inlanefreight.com
intext:"@inlanefreight.com" inurl:inlanefreight.com

Username Harvesting

We can use a tool such as linkedin2username to scrape data from a company's LinkedIn page and create various mashups of usernames (flast, first.last, f.last, etc.) that can be added to our list of potential password spraying targets.

Credential Hunting

Dehashed is an excellent tool for hunting for cleartext credentials and password hashes in breach data. We can search either on the site or using a script that performs queries via the API.

sudo python3 dehashed.py -q inlanefreight.local -p

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