A large-scale “sextortion” campaign is making use of a network of more than 450,000 hijacked computers to send aggressive emails, researchers have warned.
The emails threaten to release compromising photographs of the recipient unless $800 (£628) is paid in Bitcoin.
And they contain personal information – such as the recipient’s password – probably gathered from existing data breaches, to specifically target more than 27 million potential victims at a rate of 30,000 per hour.
While analysis suggests a small fraction of targets have fallen for the ploy, one expert said such botnets still offered a great “return on investment” for cyber-criminals.
“A botnet can be used for many, many things,” said Charles Henderson, from IBM’s X-Force Red security team. “This was just one task assigned to it.”