From the Field: Weak Service Accounts

๐Ÿ”Ž ๐—™๐—ฟ๐—ผ๐—บ ๐˜๐—ต๐—ฒ ๐—™๐—ถ๐—ฒ๐—น๐—ฑ โ€” Real-World Findings from Security Assessments

๐Ÿ’ฅ ๐Ÿฑ๐Ÿณ.๐Ÿญ%ย of infrastructures I’ve assessedย have ๐˜„๐—ฒ๐—ฎ๐—ธ ๐—ฝ๐—ฎ๐˜€๐˜€๐˜„๐—ผ๐—ฟ๐—ฑ ๐—ฝ๐—ผ๐—น๐—ถ๐—ฐ๐—ถ๐—ฒ๐˜€ ๐—ณ๐—ผ๐—ฟ ๐˜€๐—ฒ๐—ฟ๐˜ƒ๐—ถ๐—ฐ๐—ฒ ๐—ฎ๐—ฐ๐—ฐ๐—ผ๐˜‚๐—ป๐˜๐˜€.

Longer passwords for service accounts โ€” yes or no?

๐—ฆ๐—ต๐—ผ๐—ฟ๐˜ ๐—ฎ๐—ป๐˜€๐˜„๐—ฒ๐—ฟ: ๐—ฌ๐—ฒ๐˜€. But more importantly โ€” knowย ๐—ช๐—›๐—ฌ.

๐Ÿšจ Many orgs still use basic domain user accounts for services. That’s a bad idea.

๐—ช๐—ต๐˜†?

Those accounts are stored in the Windows registry (๐—ฐ๐—ฎ๐—ป ๐—ฏ๐—ฒ ๐—ฒ๐˜…๐˜๐—ฟ๐—ฎ๐—ฐ๐˜๐—ฒ๐—ฑ ๐—ถ๐—ป ๐—ฝ๐—น๐—ฎ๐—ถ๐—ป๐˜๐—ฒ๐˜…๐˜). They’re exposed to plaintext credential extraction โ€” password length doesn’t matter in that case.

So why use long passwords at all? Because ofย ๐—ž๐—ฒ๐—ฟ๐—ฏ๐—ฒ๐—ฟ๐—ผ๐—ฎ๐˜€๐˜๐—ถ๐—ป๐—ด.

๐—”๐—ป๐˜† ๐˜‚๐˜€๐—ฒ๐—ฟ in the domain can request Service Tickets (TGS) for accounts with anย SPN. The domain controller doesn’t verify who’s asking.

โ—Those TGS ticketsย are encrypted with the ๐—ธ๐—ฒ๐˜† ๐—ฑ๐—ฒ๐—ฟ๐—ถ๐˜ƒ๐—ฒ๐—ฑ ๐—ณ๐—ฟ๐—ผ๐—บ ๐˜๐—ต๐—ฒ ๐˜€๐—ฒ๐—ฟ๐˜ƒ๐—ถ๐—ฐ๐—ฒ ๐—ฎ๐—ฐ๐—ฐ๐—ผ๐˜‚๐—ป๐˜’๐˜€ ๐—ฝ๐—ฎ๐˜€๐˜€๐˜„๐—ผ๐—ฟ๐—ฑ.

Weak password = fast offline crack = attacker gets creds.

๐Ÿ› ๏ธย ๐—ช๐—ต๐—ฎ๐˜ ๐˜†๐—ผ๐˜‚ ๐˜€๐—ต๐—ผ๐˜‚๐—น๐—ฑ ๐—ฑ๐—ผ:

โ–ช๏ธ Create a custom Fine-Grained Password Policy (๐—™๐—š๐—ฃ๐—ฃ) for service accounts.

โ–ช๏ธ Ideally use better service account options:

โ–ถ๏ธ ๐— ๐—ฆ๐—” / ๐—š๐— ๐—ฆ๐—” / VSA (Managed or virtual accounts)

โ–ช๏ธ If needed, implementย ๐—”๐˜‚๐˜๐—ต๐—ฒ๐—ป๐˜๐—ถ๐—ฐ๐—ฎ๐˜๐—ถ๐—ผ๐—ป ๐—ฃ๐—ผ๐—น๐—ถ๐—ฐ๐—ถ๐—ฒ๐˜€ย to restrict who can request TGS for sensitive accounts.

๐Ÿ’ก Most people talk about Kerberoasting, few talk about why long passwords still matter โ€” even when plaintext risk exists.

Now you know.ย ๐— ๐—ฎ๐—ธ๐—ฒ ๐˜†๐—ผ๐˜‚๐—ฟ ๐—ถ๐—ป๐—ณ๐—ฟ๐—ฎ ๐˜€๐—ฎ๐—ณ๐—ฒ๐—ฟ.