The dark side of the web - The Computing Universe: A Journey through a Revolution - page 252

Cyberwarfare

The latest escalation in malware is the potential to use worms for cyber-
warfare , politically motivated hacking for purposes of spying or sabotage. It is
now believed that the Stuxnet worm discovered in the summer of 2010 was
engineered by U.S. and Israeli computer experts specifically to attack centri-
fuges at the Iranian uranium fuel-enrichment plant in Natanz, a site suspected
of being a center for building a uranium-based atomic bomb. A series of high-
speed centrifuges is needed to separate the rare, bomb-grade uranium-235
isotope from the much more common uranium-238 isotope present in ura-
nium ore. An industrial control system manufactured by Siemens AG man-
ages the centrifuges at the Natanz plant. This system uses a special-purpose
computer called a programmable logic controller (PLC) that is programmed using
Siemens software called Step-7. To spread itself throughout the plant, the
Stuxnet worm exploited several previously unknown bugs - known as zero
day bugs - in the Microsoft Windows XP operating system. In this way, the
worm seized control of the PCs and substituted its own version of Siemens's
Step-7 PLC code. This code modified the operation of the centrifuges yet
reported to the operator that everything was fine. Thus the Step-7 malware
used rootkit techniques to conceal its presence. The writers of worm code
needed a very deep knowledge of both Windows and Siemens industrial con-
trol systems as well as detailed information about the centrifuge installation
at the Natanz fuel-enrichment plant. It is likely that the worm was introduced
into the Natanz using a USB memory stick since the plant is believed to be
air-gapped - not connected to the Internet. A recent topic, Confront and Conceal ,
by New York Times reporter David Sanger, describes operation Olympic Games ,
the codename for Stuxnet development and deployment, and details how the
worm escaped to the Internet.
How much damage did Stuxnet cause? One report suggests that as many
as a thousand centrifuges at Natanz or around 10 percent of the total needed
to be replaced. In the long run, what may be of more significance than the
cyberattack on Natanz is that the Stuxnet worm represents a blueprint for the
construction of malware capable of attacking a wide range of industrial control
systems, which form a key part of the modern world's critical infrastructure.

Cryptography and the key distribution problem

The science of cryptography dates back to ancient times ( Fig. 12.10 ). It
consists of techniques for encoding the information in a message - that is, for
putting the information into a form that can only be read or decoded by the
intended recipient. According to the Roman historian Suetonius, Julius Caesar
used a method called a shift cipher to encode secret government messages:

Fig. 12.10. The word cryptos ( κρυπτός )
in Greek means hidden. This is the
Kryptos sculpture located in front of
CIA headquarter in Langley. There are
four messages on the sculpture; three of
them have been deciphered, the fourth
is so far unbroken.

If he had anything confidential to say, he wrote it in cipher, that is, by so
changing the order of the letters of the alphabet, that not a word could be
made out. If anyone wishes to decipher these, and get at their meaning, he
must substitute the fourth letter of the alphabet, namely D, for A, and so with
the others. 9