Unveiling Hidden Secrets: How to Use 'gobuster' (with examples)

Gobuster is a powerful tool commonly used by cybersecurity professionals and ethical hackers to uncover hidden paths, files, and other resources on web servers. It specializes in directory and file brute-forcing but extends its capabilities beyond basic functions, offering options to discover subdomains, S3 buckets, virtual hosts, and even parameter fuzzing. By leveraging a specified wordlist, gobuster attempts various permutations to identify hidden elements that are not immediately visible or accessible via standard web browsing or directory listings.

Discover directories and files that match in the wordlist

Code:

gobuster dir --url https://example.com/ --wordlist path/to/file

Motivation: One of the primary motivations for this use case is to identify hidden directories and files within a web server that are not linked openly through the web interface. These hidden paths could reveal vulnerable or sensitive information that might be overlooked. By using a wordlist, gobuster can effectively attempt to access all possible directory and file names listed, uncovering paths like /admin, /backup, or undocumented files that could present security issues.

Explanation:

• dir: This subcommand specifies that gobuster is performing a directory search.
• --url https://example.com/: Indicates the target URL where the search for directories and files will occur.
• --wordlist path/to/file: This argument points to the file containing potential directory and file names that gobuster will use to brute-force the web server.

Example Output:

/admin (Status: 302)
/backup (Status: 200)
/test.php (Status: 404)

This output implies that a /admin path exists and is potentially redirecting, /backup is accessible, and /test.php was attempted but not found.

Discover subdomains

Code:

gobuster dns --domain example.com --wordlist path/to/file

Motivation: Discovering subdomains is crucial because these subdomains can contain separate applications, services, or admin areas that are not listed on the main website. These areas can represent additional attack surfaces, where security settings may not be as robust or regularly audited as the main site.

Explanation:

• dns: This subcommand is used for subdomain enumeration.
• --domain example.com: Specifies the target domain for which gobuster will identify subdomains.
• --wordlist path/to/file: Provides the path to the file containing potential subdomain names to check against the domain.

Example Output:

mail.example.com
ftp.example.com
dev.example.com

This output reveals existing subdomains which may warrant further examination.

Discover Amazon S3 buckets

Code:

gobuster s3 --wordlist path/to/file

Motivation: Amazon S3 buckets can sometimes be misconfigured, leading to unintended public access. Brute-forcing S3 bucket names can reveal storage that might contain confidential data artifacts, private media, or server backups, making them targets for data breaches.

Explanation:

• s3: Directs gobuster to search for S3 buckets.
• --wordlist path/to/file: The wordlist of potential bucket names that gobuster uses in its attempts to discover accessible S3 buckets.

Example Output:

myapp-backup (Status: 403)
logs-storage (Status: 200)

This indicates a private bucket (403) and one that is accessible with public exposure (200).

Discover other virtual hosts on the server

Code:

gobuster vhost --url https://example.com/ --wordlist path/to/file

Motivation: Finding virtual hosts can expose independently-run sites or applications on the same server, potentially with different security postures or roles, that a single server’s main website cannot account for. This could include test environments or deprecated backup sites that should be offline but haven’t been adequately secured.

Explanation:

• vhost: Specifies that gobuster should search for virtual hosts.
• --url https://example.com/: Base URL for identifying additional virtual hosts.
• --wordlist path/to/file: Points to the file of prospective virtual host names.

Example Output:

sales.example.com (Status: 200)
forum.example.com (Status: 403)

This result lists virtual hosts, suggesting accessible services and those with restricted access.

Fuzz the value of a parameter

Code:

gobuster fuzz --url https://example.com/?parameter=FUZZ --wordlist path/to/file

Motivation: Fuzzing parameter values helps identify viable values that can be manipulated for potential vulnerabilities or information leaks. It’s particularly useful in situations where the parameters accepted by a web application are unknown or not fully documented.

Explanation:

• fuzz: Engages the parameter value fuzzing mode in gobuster.
• --url https://example.com/?parameter=FUZZ: Specifies the URL and indicates the parameter to be fuzzed (FUZZ placeholder).
• --wordlist path/to/file: Contains possible values for the parameter parameter to discover accessible or responsive values.

Example Output:

TEST1 (Status: 400)
VALID (Status: 200)

Suggests that VALID is an accepted parameter value, potentially leading to different behavior.

Fuzz the name of a parameter

Code:

gobuster fuzz --url https://example.com/?FUZZ=value --wordlist path/to/file

Motivation: By fuzzing parameter names, one can reveal hidden or undocumented parameters that interact with the web application, potentially providing unauthorized functionality or information.

Explanation:

• fuzz: Signals that we are fuzzing parameter names rather than their values.
• --url https://example.com/?FUZZ=value: The endpoint URL with FUZZ indicating where the fuzzing takes place in the parameter name position.
• --wordlist path/to/file: The file containing potential parameter names to attempt against the URL.

Example Output:

api_key (Status: 200)
sessionid (Status: 404)

This suggests that there is a parameter api_key that is accepted by the web application.

Conclusion:

Gobuster offers a multitude of features for uncovering hidden elements across web-related assets, with implementations ranging from directory and subdomain discovery to fuzzing parameters critical for cybersecurity analysis. Whether employed for strengthening security defenses or in legitimate penetration testing scenarios, gobuster remains an essential tool in the cybersecurity toolkit, providing insights that might otherwise remain concealed.