Miscreants have created a ransomware Trojan for mobile phones which has been seen in the wild in China. Kiazha-A, attempts to extort money from users of Symbian Series 60 phones.

Infected smartphones display a message saying that victims need to send RMB 50 ($7) to the malware authors in order to regain use of the phone. The message (roughly translated) states: "Warning: Your device has been affected, please prepare a recharge card of RMB 50 yuan and connect QQ[id removed] account, or your phone will be paralysed!!!"

QQ is a popular instant messaging network in China that's become the target of many password stealing Trojans and scams over recent months. The network supports its own currency, called QQ coins, that can be traded.

An analysis by anti-virus firm McAfee has found that Kiazha-A is a component of a sophisticated mobile malware bundle, dubbed MultiDropper-CR. SMS messages on infected devices are controlled by hackers to set up an elaborate scam, McAfee explains. Initial infection is spread via either Bluetooth or tainted MMS messages from other infected devices.

"MultiDropper-CR uses malicious payloads (Beselo, Commwarrior) to convince the user their phone is infected. It also sets up SMS forwarding (SmsSend-G) to collect information and potentially passwords. In case the victim doesn’t have a QQ account the malware will order (SmsSend-F) one for them. After all that, Kiazha-A deletes SMS messages to cover its tracks and displays the offer to fix the user’s phone for a small fee," writes McAfee anti-virus analyst Jimmy Shah.

Multidroppers are usually put together by miscreants using components they haven't created themselves, a pattern repeated with the Kiazha money-making scam. "It appears that the author, with a lot of effort and testing, put together various malware like pieces from a toolkit, Shah adds.

China has become a hotspot of mobile malware of late. Last month a Trojan capable of infecting mobile devices running Windows CE surfaced in the republic.

The InfoJack Trojan is spread by either tricking mobile users into installing seemingly legitimate application installation files (that posed as stock trading apps or games, for example) or if punters inadvertently use an infected memory card on vulnerable devices.

The malware disabled Windows Mobile application installation security, allowing further malware components to be surreptitiously installed without user intervention or knowledge. InfoJack sent the infected device's serial number, operating system, and other information to the author of the Trojan. ®

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