1. A method of detecting unknown malware on a computer, the method comprising: using the computer to scan code stored in a system memory of the computer, and/or code being injected into the system memory, for the presence of known Universal Resource Locators and/or partial Universal Resource Locators identifying trusted websites, which known Universal Resource Locators or partial Universal Resource Locators may be used by malware during execution of the malware, and, upon detecting a known Universal Resource Locator and/or partial Universal Resource Locator that identifies a trusted website, locating the source of suspect code containing the detected known Universal Resource Locator and/or partial Universal Resource Locator and determining whether or not the source is an authorised source and, if not, identifying the source as potential malware.