Botnet Operators Infecting Servers, Not Just PCs

By Kelly Jackson Higgins
DarkReading
Dec 16, 2009

Botnet operators have always been able to easily infect and convert PCs
into bots, but they also are increasingly going after servers -- even
building networks of compromised servers.

Web servers, FTP servers, and even SSL servers are becoming prime
targets for botnet operators, not as command and control servers or as
pure zombies, but more as a place to host their malicious code and
files, or in some cases to execute high-powered spam runs.

"FTP servers are a hot commodity in the underground. They are regularly
used by drive-by download malware as well as a downloading component for
regular bots," says Mikko Hypponen, chief research officer at F-Secure.
"Another thing we've noticed is the use of SSL servers. Sites with a
valid SSL certificate get hacked and are used by drive-by-downloads."

Why SSL servers? "If a drive-by download gets the malware file through
an HTTPS connection, proxy and gateway scanners won't be able to scan
for the malware in transit, making it easier to sneak in," Hypponen
explains.