Learn Finnish: Pomo suuttui huonosta tietoturvasta. - The boss got angry about the bad data security.

This is driven by the verb suuttua (to get angry). In Finnish, when you express what causes the anger, suuttua requires the elative case (-sta/-stä). You literally get angry 'out of' something.

How does suuttui differ from saying oli vihainen?

Suuttua describes an active change of state meaning 'to get angry' or 'to lose one's temper'. Oli vihainen describes a continuous state of being ('was angry'). The grammar also changes: you are angry at someone using the allative case (vihainen jollekin), but you get angry about something using the elative (suuttua jostakin).

How is the word tietoturvasta constructed?

It is a standard compound word made of tieto (information, data) and turva (security, protection). The -sta ending is the elative case marker required by the main verb.

Why does the adjective huono also take the -sta ending here?

This is a classic case of adjective agreement. In Finnish, adjectives that modify a noun must match that noun in both case and number. Since the noun tietoturvasta is in the elative case, the adjective huono (bad) must also take the elative ending, becoming huonosta.