Exploit.ByteVerify is a means of penetration into computers using the vulnerability in Microsoft Virtual Machine, build 5.0.3809 inclusive. The detailed description of this flaw in Microsoft’s software appeared in our news dated 09.04.2003.
The disclosure of the vulnerability and the patch release gave birth to a series of Trojan Horses, utilizing this exploit.
The computer becomes Trojan affected at simple viewing of a web-site with malicious Java-script embedded into it. Another way for them to tunnel into systems is to be executed by a user himself from HTML- attachment, received vi e-mail. An ill-intentioned Java-applet downloads from the internet and installs a Trojan program exploiting the ByteVerify vulnerability. Besides, the Trojan of this family can perform the following actions in the victimized machine:
- it secures its automatic launch at every system startup
- the Troj may considerably degrade the performance of Internet Explorer
- when alphabetic symbols are typed into specified fields they will be displayed on the screen with some delay
- if non-existing URL mistyped by a user or the address without www is entered into a search bar the default «Server is not found» page will not appear, instead, the browser will be redirected to a web-site determined in the Trojan’s code
- links to dubious web-sites are added into Favourites folder
- search bar is replaced
- user stylesheet is replaced with Trojan’s own stylesheet file
- when searching with Google, Yahoo, MSN and Altavista the Troj provoke multiple popup windows to show up
- it can disguise its presence in a system as a driver update