Zalo warns users of remote account monitoring and SIM‑recycling security risks

Zalo, Vietnam’s leading messaging app, issued a series of security advisories. It warned users to look for signs of unauthorized remote access, such as login alerts from unknown devices, messages that appear read or deleted without user action, and unexpected changes in chat status. The platform advised checking the device‑login list in Settings → Account → Security, logging out unfamiliar devices, using strong passwords, enabling two‑factor authentication, and never sharing OTP codes. Zalo also highlighted phishing tactics that mimic financial institutions and direct users to counterfeit login pages.

In a separate rollout, Zalo announced a partnership with Viettel to audit phone numbers linked to user accounts. Numbers that have been reclaimed or are no longer active – a growing issue known as “SIM turnover” – will trigger notifications prompting users to update their registered numbers. The update process is performed via Settings → Account → Phone Number, followed by OTP verification. The initiative aims to prevent hijacked accounts, reduce spam, and curb illicit use of dormant numbers.

Both measures are intended to protect personal data, block fraudulent messaging, and improve overall account safety for Zalo’s millions of users.