Could botnets - the scourge of consumer security - be on the verge of going mobile? The prospect seems some way off but even so mobile operators and security watchers are more than a little spooked.
Job de Haas, a researcher at security firm ITSX, told delegates at the recent Black Hat conference in Amsterdam that client side browser exploits on mobile phones pose a serious risk. In theory, a successful compromise could be used to turn smartphones into proxies under the control of hackers, controlled over VoIP connections. Risks include toll fraud, the installation of auto diallers, and sending high cost SMS/MMS messages. "Currently Symbian is not prepared for serious attacks," de Haas, whose previous research revealed how malformed SMS messages could be used to crash mobiles, added.
The increased computing power in the latest smartphones leaves them more vulnerable to viral attack but getting users to download and install malign code remains a huge barrier, unlike the Windows PC arena. Trojans such as Phatbot are often used to seize control of Windows PCs, turning them into zombie clients in networks of compromised PCs (botnets). These botnets are used to send spam or as platforms for DDoS attacks, carrying out criminal attacks right under the noses of their rightful owners.
Mobile industry representatives present at de Haas's presentation on Symbian Security discounted the immediate threat of 'mobile botnets' and said there were still several barriers to overcome before an attack that might yield control of substantial numbers of Symbian-based smartphones could even be seriously attempted.
Mobile malware menace
Mobile viruses, such as Cabir, spread between mobile phones running Symbian Series 60 using Bluetooth technology. More recent viruses, such as CommWarrior, can spread using MMS. But incidents of infection by such viruses are rare and unknown without user interaction. "So-far all of known attacks have needed user confirmation. Often more than once," de Haas said.
Even though the threat from mobile viruses - much less mobile botnets - is still low a representative from a leading European mobile carrier told El Reg that was it considered one of the greatest security threats it faced this year.
Patrik Runald, senior technical consultant at F-Secure, said remotely executable code on mobiles remains unknown. "Without an exploit you’d have to trick people into executing a maliciously constructed MMS file, spammed out in an attempt to seize control of multiple smartphones, or something like that. People are more used to downloading and executing files on PCs than on mobiles so it’s much harder to spread malicious code on mobiles."
"Apart from the built-in billing system on mobiles, I don't know why anyone would want to build a mobile botnet. A broadband-connected PC has a much faster connection than a mobile and it’s less likely to be turned off, so the connection is more stable. Attackers can make money from compromised PCs through porn dialler scams, for example." ®
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