The Colaba police have registered a cyber fraud case against unknown persons, while a parallel investigation has been launched by the Maharashtra Cyber Cell, based on a complaint filed by a naval staffer who was allegedly duped of Rs 90,811.

According to the police, the fraudsters sent a fake APK mobile application to the 27-year-old naval employee posted at the Naval Dockyard in Colaba, gaining unauthorised access to his mobile phone and misusing his credit cards.

Police said that the victim received a WhatsApp message around 5 pm on January 10 containing an APK file labelled as an IndusInd Bank credit card application. As the victim holds an IndusInd , he allegedly downloaded the file, believing it to be genuine.

Gone in minutes

Police said that shortly after the APK file was downloaded, the victim began receiving transaction alerts from two different credit cards. One transaction was allegedly carried out in the name of Reliance Retail Limited, while another transaction was made through One MobiKwik Systems. In total, the fraudsters allegedly siphoned off Rs 90,811 from the two credit cards before the victim could react, police said.

Realising that he had been cheated, the naval staffer immediately contacted the national cyber crime helpline number 1930 and lodged an online complaint. Police said that soon after, he received another call from an unknown number, with the caller allegedly posing as a bank manager and demanding Rs 2499 on the pretext of stopping the annual credit card fee. The victim grew suspicious and did not make any further payment.

The complainant told police that the fake APK application allegedly allowed the fraudsters to gain remote control of his handset and misuse his credit cards. A case has been registered, and investigators are tracing the digital trail, mobile numbers and beneficiary accounts, police said.

‘Beware of .apk files’

Police have cautioned against downloading APK files received via WhatsApp or SMS, even if they appear to be from banks or government agencies.