Drever.A is a SIS file trojan that tries to disable Simworks Anti-Virus and Kaspersky Anti-Virus. Locknut.B is a new variant of Locknut trojan family, which disables phone so that it can be disinfected only with special disinfection tool.

Locknut.B is a malicious SIS file trojan that pretends to be patch for Symbian Series 60 mobile phones. When installed Locknut.B drops a binary that will crash a critical System component, that will prevent any application from being launched in the phone. Thus effectively locking the phone.

http://www.f-secure.com/v-descs/locknut_b.shtml

Drever.A is a malicious SIS file trojan that disables the automatic startup from Simworks and Kaspersky Symbian Anti-Virus softwares. Currently it is still unverified whether either of these softwares have protection against such attacks.

http://www.f-secure.com/v-descs/drever_a.shtml