Student, do you use Telegram or WhatsApp? Here’s how to protect your account
The National Cyber Security Centre announced at the beginning of the year that WhatsApp and Telegram account hijacks and attempted hijacks have increased. Accounts have been hijacked, for example, through the linking function or by the hijacker re-registering the account on their device using a verification code.
WhatsApp’s device linking function allows you to use the same WhatsApp account with another device, such as a computer. However, the linking function is also used in account hijacking attacks, in which the hijacker links their own device to the WhatsApp account. If the hijacker gains access to the WhatsApp account via the link, they can read and send messages in real time.
Instant messaging accounts can also be hijacked using the voicemail. The attack is based on the fact that many users have a default or very weak PIN code in their voicemail, and it is also possible to listen to messages from another number by calling the voicemail using the PIN code. The National Cyber Security Centre is aware of data breaches in which Telegram accounts have been successfully hacked using the voicemail. In the case of the Telegram service, the breach occurs so that when the hacker attempts to register an account with another number, the service first sends a verification code as an SMS. After two minutes, you can also receive the verification code by phone. If the incoming call with the verification code ends up in the voicemail, the hacker calls the victim’s voicemail, identifies with a weak PIN code and, thereby, obtains the verification code.
Protect your instant messaging accounts
- against re-registration with two-factor authentication
- by checking that there are no unknown devices connected to your account
- by making sure that the voicemail PIN for your phone subscription is not the default PIN
- by being careful when you receive a message regarding the service registration or other verification code
- Read more on the National Cyber Security Centre's website.
Read more digital security tips:
- Digital security review 1/2026 on Flamma (requires login)
- Remember also the Students’ IT services page
- Are you wondering about the safe use of AI? Listen to the latest episode of the Korkeakoulujen tietoturvaajat podcast (only in Finnish), where AI experts Laura Tiilikainen and Pekko Vehviläinen discuss the topic!