Microsoft has issued security patches for several vulnerabilities that administrators need to ensure are fixed, according to experts. Several allow an attacker to take complete control of a compromised system.

One Internet Explorer vulnerability (MS08-023) only requires users to follow a link to a specially crafted web page to be affected, warns security firm Lumension.

The vulnerability addressed by MS08-020 for Windows DNS Clients also needs to be dealt with promptly by firms that are affected, as this would allow internet traffic from legitimate locations to be spoofed or redirected, according to Lumension.