The 100,000 employees and students at the Hogeschool van Amsterdam (HvA) and University of Amsterdam (UvA) will be advised from Tuesday to change their passwords for the school systems.
The two institutions were the target of a cyber attack last week.
The institutions found out on Tuesday that the attackers had access to the passwords, an AUAS spokesperson told NU.nl.
That is why the institutions recommend students and staff to change their passwords.
Whether the attackers will actually have access to the passwords is not certain, but the university and college want to "be on the safe side".
Pupils and employees are informed by e-mail.
Because it involves many emails, the students and employees are notified in phases.
Both educational institutions announced on Wednesday that they had been hit by a cyber attack.
They saw the first signs of this two days earlier.
The hackers probably wanted to carry out a ransomware attack, the spokesperson told NU.nl.
This would appear from traces they have left.
Hackers encrypt the computer systems in such an attack.
They only release these when a ransom is paid.
The investigation of the cybersecurity department of the educational institutions is still ongoing.
The spokesperson says that not all servers have been investigated yet.
The department said earlier that it concerns professional hackers who were after money.
The educational institutions do not want to provide more information about the attackers, so as not to disrupt the investigation.
The educational institutions also warn against phishing emails circulating about the hack.
The spokesperson tells NU.nl that other attackers may want to abuse the cyber attack.
In those emails, the attackers pretend to be the educational institutions and ask recipients, for example, to change their password via a link.
In reality, this link does not lead to a site of the educational institutions, but to one of the attackers.
They then intercept the data entered by the student or employee.
See also: AUAS and UvA report cyber attack: 'Education will continue as usual'