The messages that came from handles such as "Lam tinh" (Making love), "Gai goi" (Call girl) and "Tim ban tinh" (Seeking love partners) began at the end of February, and have increased since last week.
Phuong Thanh in Hanoi’s Cau Giay District said she received text messages from obscene sender names twice last week.
When she was dining out with friends once the entire group received a message from the same sender with identical content telling to access a link for details.
Thanh Lam in Ho Chi Minh City’s District 1 said he has received similar messages in the last few days. When he clicked on the link that came with the message, he was redirected to a website that introduced a dating app and told users to download it.
"I knew it was a scam, so I didn’t go ahead. However, it will be very dangerous if the bad guys use aliases to impersonate organizations such as network carriers, banks and e-wallets," he said. "Then gullible people are very likely to be deceived."
Many phone users received messages with obscene content.
The difference with the old scam is that the obscene messages do not display a phone number, only a preset sender name.
In telecommunications, it is known as an "alias," and is used only in brand-name messages registered by companies and owners of product brands.
Computer security expert Ngo Minh Hieu, aka HieuPC, the founder of a non-profit named "Chong lua dao" (Anti-phishing), said scammers change scripts constantly.
"When phone users are wary of messages impersonating banks, scammers turn to scenarios that target curiosity."
The applications that are sent for downloading are mainly spyware capable of collecting user information, he said.
Experts advise phone users not to click on unknown links, carefully check a website before downloading apps or entering passwords and set up OTP (one-time password) security for accounts and install security software on their computers and mobile phones.