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Kerberos ticket mishaps, especially those related to Base64 encoding errors, can be a significant headache for security professionals. Tools like Rubeus, Impacket, and Mimikatz often fail when tickets contain unexpected spaces or line breaks, leading to errors such as:
– `struct.error: unpack requires a buffer of 1 bytes`
– `base64: invalid input`
These issues can consume valuable time during troubleshooting. However, addressing these problems during ticket generation, rather than after, can save you hours of frustration.
You Should Know:
1. Removing Spaces in Base64 Tickets
Use the following command to remove spaces and line breaks from a Base64-encoded Kerberos ticket:
cat ticket.txt | tr -d ' \n' > cleaned_ticket.txt
This command uses `tr` to delete spaces and newline characters, ensuring the ticket is properly formatted.
2. Generating Kerberos Tickets with Rubeus
When generating tickets with Rubeus, ensure the output is clean by piping it through tr:
Rubeus.exe asktgt /user:admin /domain:example.com /rc4:hash | tr -d ' \n' > kerberos_ticket.kirbi
3. Using Impacket for Ticket Injection
If you’re using Impacket’s ticketConverter.py, clean the ticket first:
python3 ticketConverter.py cleaned_ticket.txt ticket.ccache
4. Mimikatz and Base64 Tickets
Mimikatz can also handle Base64 tickets, but ensure the input is clean:
mimikatz # kerberos::ptt cleaned_ticket.kirbi
5. Automating the Process
Create a script to automate the cleaning process:
#!/bin/bash input_ticket=$1 output_ticket=$2 cat $input_ticket | tr -d ' \n' > $output_ticket echo "Ticket cleaned and saved to $output_ticket"
What Undercode Say:
Kerberos ticket mishaps, particularly those involving Base64 encoding errors, are a common yet avoidable issue. By addressing formatting problems during ticket generation and using tools like tr, Rubeus, Impacket, and Mimikatz effectively, you can streamline your workflow and avoid unnecessary troubleshooting. Always ensure your tickets are clean and properly formatted before injection.
For further reading, check out the full blog post: Careful with Spaces on Kerberos Tickets.
Related Commands:
– `klist` – List Kerberos tickets in the cache.
– `kinit` – Obtain and cache Kerberos tickets.
– `kdestroy` – Destroy Kerberos tickets.
– `kvno` – Acquire a service ticket for a specified principal.
– `kadmin` – Manage Kerberos principals and policies.
By mastering these commands and techniques, you can enhance your database and system security while minimizing errors.
References:
Reported By: Activity 7306105647152996353 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
