Lack of voice recognition or authentication mechanism is a threat to security, says expert.
Voice recognition technologies found in iOS, Android and other Internet of Things (IoT) based devices are vulnerable to over-the-air-attacks, security firm AVG said.
The devices using voice assistant are not capable of voice recognition as they are not configured for individual voices, making them vulnerable to hacking.
The security firm reported that hackers could execute commands on the victim’s device and take control of the device.
BBC reported AVG CTO Yuval Ben-Itzhak saying: "It would obviously be preferable if devices were to learn our voices, and ask for some form of authentication if they determined that an unauthorized user might be giving commands.
"If malware can get on an Android device to speak a command and order the Android to send an unauthorised email, it could just as easily do that without using speech."
Yuval demonstrated the vulnerability by turning on a smart TV with synthesised voice, and said that similar attacks could be made on Android and iOS devices.
Voice assistance may be used in smart home assistance security systems, for vehicles and connected work spaces but without voice authentication systems, these systems could become vulnerable to attack.
"Utilizing voice activation technology in the Internet of Things without authenticating the source of the voice is like leaving your computer without a password – everyone can use it and send commands," Ben-Itzhak added.