Subdomain enumeration is the process of identifying all subdomains for a
given domain. This can be useful for a variety of purposes, such as
identifying potential targets for an attack, or simply for organizational
purposes. It also helps to broader the attack surface, find hidden
applications, and forgotten subdomains.
Importance of Subdomain:
There are several reasons why you might want to enumerate all
subdomains for a given domain:
o To identify potential targets for an attack: By enumerating all
subdomains, you may be able to find subdomains that are less well protected than the root domain or the target organization, making
them more vulnerable to attack.o To gain insights into the organization: Subdomain enumeration can
give you insights into how an organization is structured, what
services they offer, and so on. This information can be valuable when
performing reconnaissance for a penetration test or security
assessment.o To find misconfigured DNS entries: In some cases, organizations may
have misconfigured DNS entries that reveal sensitive information,
such as internal IP addresses.
From an attacker’s point of view, subdomain enumeration can be used to
find potential vulnerabilities. For example, if an organization has a blog
hosted at blog.example.com, and the blog software is not kept up to date,
an attacker may be able to exploit it and gain access to the main example.com domain. Vulnerable subdomains can also be used to launch
phishing attacks or other types of social engineering attacks through
subdomain takeover attacks. Starting from internet wide scan data or an
ip address pool attackers can derive a list of multiple domains that might
be interesting to harvest sub domains. Or they could decide to target a
specific domain or multiple subdomains to start their attacks on.
Organizations can use subdomain enumeration for a variety of purposes,
such as inventorying their owned domains, or identifying which domains
are being used for which purposes. This can be helpful in organizational
security efforts, as it can help identify potential weak points that may need
to be addressed. It is also really helpful to find old, deprecated, and
potentially vulnerable applications hosted on subdomains of which no one
still knows why they exist or who maintains them.
TOOLS:
- Knockpy: Knockpy is a python tool designed to enumerate subdomains on a target domain through a wordlist.
2. Sublist3r: Sublist3r is a tool designed in python and uses OSINT in order to enumerate subdomains of websites. It can help pentesters in collecting and gathering subdomains for a domain which is their target.
3. Subfinder: Subfinder is a subdomain discovery tool that discovers valid subdomains for websites. Designed as a passive framework to be useful for bug bounties and safe penetration testing.
4. Httpx: Httpx is a fast and multi-purpose HTTP toolkit that allows running multiple probes using the retryablehttp library. It is designed to maintain result reliability with an increased number of threads.
5. SubBrute: SubBrute is a community driven project with the goal of creating the fastest, and most accurate subdomain enumeration tool SubBrute is a free and open-source tool available on GitHub. SubBrute uses DNS Scan for finding subdomains of the target domain.
