Some 52 previously unknown trojans targeting mobile phone operating system Symbian appeared in the 24 hours ending 20 April, a security firm said.
Aaron Davidson, chief executive at mobile phone-focused anti-virus vendor SimWorks, said the company had identified 52 previously unknown Symbian trojans in one day -- twice the number of all malware targeting Symbian identified to date.
“Until now, we've usually found mobile trojans two or three at a time at the most," he said.
Although a malware writer could create one trojan and give it 52 different names, that wasn't what had happened here, he said.
"This is not the case here, where we have 52 separately cracked and infected applications. Somebody has gone to an awful lot of time and effort to turn these out," Davidson said.
The trojans appeared to be cracked versions of popular Symbian applications such as
BitStorm, BugMe!, Cosmic Fighter, 3D Motoracer and SplashID. The files also included various versions of previously known malware such as Cabir and Locknut, he said.
All 52 trojans targeted Series 60 phones running Symbian's version 6 operating system. None targeted UIQ-based Symbian phones such as the SonyEricsson P900/910 and Motorola A925/1000, Davidson said.
“Previous mobile viruses have either been able to spread but cause no harm or have been able cause significant harm but not able to spread," he said.
Davidson speculated that the large number of harmful trojans found in one day meant malware writers wanted to improve the odds of someone actually downloading and installing the trojans.
However, SimWorks had yet to receive any reports of the 52 new trojans in the wild at the time of writing. “Until reports are received of these trojans in the wild, there is little risk to end users," Davidson said.
However, all 52 appeared ready to release. Putting all 52 on one website would make downloading from it like playing Russian roulette, he said.
"Every other file could contain something that could cause your phone to be corrupted requiring a factory reset or worse," Davidson said.
Security vendor Trend Micro confirmed that mobile phone malware was on the increase. Some mobile phone malware could infect mobile phones and computers simultaneously, the vendor said in a statement.
"A recent report from Trend Micro’s TrendLabs indicates mobile malwares have not only advanced at a surprising rate in the last three months in terms of technology and range of infection, but most users have found them very difficult to remove," Trend Micro said.