IRCBot.ZK is a worm that spreads by copying itself, without infecting other files. It captures certain information entered or saved by the user, with the corresponding threat to privacy:
passwords saved by certain Windows services; keystrokes, in order to obtain information for accessing online banking services, passwords and other confidential information. It sends the gathered information to a remote user by any available means: email, FTP, etc. It reduces the security level of the computer:
it terminates processes belonging to security tools, such as antivirus programs and firewalls, leaving the computer defenseless against attacks from other malware; it notifies the attacker that the computer has been compromised and is ready to be used maliciously; it opens one or more ports to allow remote access to the computer and takes action that compromises user confidentiality; it awaits remote-control orders received through
IRC or FTP; it changes system permissions, decreasing the security level. IRCBot.ZK prevents access from programs to websites of several companies related with security tools (antivirus programs, firewalls, etc.). It uses stealth techniques to avoid being detected by the user: - It uses techniques included in its code to hide itself while it is active.
- It terminates processes corresponding to several security tools, such as antivirus programs and firewalls, to prevent detection.
- It deletes the original file from which it was run once it is installed on the computer.
- It modifies system permissions in order to hide itself.
It uses several methods in order to avoid detection by antivirus companies: - It terminates its own execution if it detects that a memory dump program is running, such as Procdump.
- Its code is encrypted and it is only decrypted when it is going to run. Because of this, its code is not legible through a memory dump.
IRCBot.ZK uses the following propagation or distribution methods: - Exploiting vulnerabilities with the intervention of the user: exploiting vulnerabilities in file formats or applications. To exploit them successfully it needs the intervention of the user: opening files, viewing malicious web pages, reading emails, etc.
- Via Internet, exploiting remote vulnerabilities: attacking random IP addresses, in which it tries to insert a copy of itself by exploiting one or more vulnerabilities.
- IRC: It sends a copy of itself to all users connected to the channel to which the infected user is connected.
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