KrbGuess – Guess/Enumerate Kerberos User Accounts


KrbGuess is a small and simple tool which can be used during security testing to guess valid usernames against a Kerberos environment. It allows you to do this by studying the response from a TGT request to the KDC server. The tool works against both Microsoft Active Directory, MIT and Heimdal Kerberos implementations. In addition it will detect if an account lacks pre-authentication.

The tool is supplied with a file containing a list of usernames and requests a TGT for each user and then waits for the response. If the KDC responds with a valid TGT or with an error message stating that pre-authentication is required, a valid username has been discovered. Several guesses can be run in parallel (currently only against a single KDC) in order to improve performance.


Be careful not to run with to many threads and low timeouts as it will bring the KDC to its knees during the time of the test. The default values have been tuned against a virtual machine, and currently eat somewhere around 80% CPU which gives me roughly 700 guesses per second. In most cases the network throughput won’t be the performance bottleneck. So far I’m seeing that 2-3MBit of queries is generating a sustained 100% CPU load against both Heimdal on Ubuntu and Windows 2003.

The tool is written in Java and does not rely on any Kerberos libraries to perform the guessing. In order to successfully run the tool against a system it needs at least the realm, dictionary and a server parameters to be set. eg.

You can download KrbGuess here:

krbguess-0.21-bin.tar.gz

Or read more here.

Posted in: Hacking Tools, Networking Hacking, Password Cracking

, , , , , , , ,


Latest Posts:


zBang - Privileged Account Threat Detection Tool zBang – Privileged Account Threat Detection Tool
zBang is a risk assessment tool for Privileged Account Threat Detection on a scanned network, organizations & red teams can use it to identify attack vectors
Memhunter - Automated Memory Resident Malware Detection Memhunter – Automated Memory Resident Malware Detection
Memhunter is an Automated Memory Resident Malware Detection tool for the hunting of memory resident malware at scale, improving threat hunter analysis process.
Sandcastle - AWS S3 Bucket Enumeration Tool Sandcastle – AWS S3 Bucket Enumeration Tool
Sandcastle is an Amazon AWS S3 Bucket Enumeration Tool, formerly known as bucketCrawler. The script takes a target's name as the stem argument (e.g. shopify).
Astra - API Automated Security Testing For REST Astra – API Automated Security Testing For REST
Astra is a Python-based tool for API Automated Security Testing, REST API penetration testing is complex due to continuous changes in existing APIs.
Judas DNS - Nameserver DNS Poisoning Attack Tool Judas DNS – Nameserver DNS Poisoning Attack Tool
Judas DNS is a Nameserver DNS Poisoning Attack Tool which functions as a DNS proxy server built to be deployed in place of a taken over nameserver to perform targeted exploitation.
dsniff Download - Tools for Network Auditing & Password Sniffing dsniff Download – Tools for Network Auditing & Password Sniffing
Dsniff download is a collection of tools for network auditing & penetration testing. Dsniff, filesnarf, mailsnarf, msgsnarf, URLsnarf, and WebSpy passively monitor a network


2 Responses to KrbGuess – Guess/Enumerate Kerberos User Accounts

  1. d3m4s1@d0v1v0 October 30, 2009 at 6:31 pm #

    wow looks very interesting! I would like to test it on my work network, but the domain administrator would kill me hehehe

  2. the legend November 5, 2009 at 11:03 am #

    sodmg need a new hacker