Computer Misuse Act 1990

3 Unauthorised modification of computer material

(1) A person is guilty of an offence if—

(a) he does any act which causes an unauthorised modification of the contents of any computer; and

(b) at the time when he does the act he has the requisite intent and the requisite knowledge.

(2) For the purposes of subsection (1)(b) above the requisite intent is an intent to cause a modification of the contents of any computer and by so doing—

(a) to impair the operation of any computer;

(b) to prevent or hinder access to any program or data held in any computer; or

(c) to impair the operation of any such program or the reliability of any such data.

(3) The intent need not be directed at—

(a) any particular computer;

(b) any particular program or data or a program or data of any particular kind; or

(c) any particular modification or a modification of any particular kind.

(4) For the purposes of subsection (1)(b) above the requisite knowledge is knowledge that any modification he intends to cause is unauthorised.

(5) It is immaterial for the purposes of this section whether an unauthorised modification or any intended effect of it of a kind mentioned in subsection (2) above is, or is intended to be, permanent or merely temporary.

(6) For the purposes of the [1971 c. 48.] Criminal Damage Act 1971 a modification of the contents of a computer shall not be regarded as damaging any computer or computer storage medium unless its effect on that computer or computer storage medium impairs its physical condition.

(7) A person guilty of an offence under this section shall be liable—

(a) on summary conviction, to imprisonment for a term not exceeding six months or to a fine not exceeding the statutory maximum or to both; and

(b) on conviction on indictment, to imprisonment for a term not exceeding five years or to a fine or to both.