  Traditionally, "Cryptography" is a benediction to information processing and
communications, it helps people to store information securely and the private
communications over long distances. Cryptovirology is the study of applications
of cryptography to build the malicious software. It is an investigation, how
modern cryptographic tools and paradigms can be used to strengthen, develop and
improve new malicious software attacks. Cryptovirology attacks have been
categorized as : give malware enhanced privacy and be more robust against
reverse-engineering, secondly give the attacker enhanced anonymity while
communicating with deployed malware. This paper presents the idea of
"Cryptovirology" which introduce a twist on how cryptography can also be used
offensively. Being offensive means, it can be used to mount extortion based
attacks that cause loss of access to information, loss of confidentiality, and
information leakage, tasks which cryptography usually prevents. Also analyze
threats and attacks that misuse of cryptography can cause when combined with
fraudulent software (viruses, Trojans). Public-key cryptography is very
essential for the attacks that based on cryptovirology. This paper also suggest
some of the countermeasures, mechanisms to cope with and prevent such attacks.
Even if the attackers actions on the host machine are being monitored, it still
cannot be proven beyond reasonable doubt that he or she is the attacker; and it
is an "originator-concealing attack". Evidence should be collected from the
"author's own system which was used for the attack". These attacks have
implications on how the use of cryptographic tools and techniques should be
audited and managed in general purpose computing environments, and imply that
access to the cryptographic tools should be in well control of the system(such
as API routines).
