Malware
A specific component of anti-virus and anti-malware software, commonly referred to as an on-access or real-time scanner, hooks deep into the operating system's core or kernel and functions in a manner similar to how certain malware itself would attempt to operate, though with the user's informed permission for protecting the system. Any time the operating system accesses a file, the on-access scanner checks if the file is a 'legitimate' file or not. If the file is identified as malware by the scanner, the access operation will be stopped, the file will be dealt with by the scanner in a pre-defined way (how the anti-virus program was configured during/post installation), and the user will be notified. This may have a considerable performance impact on the operating system, though the degree of impact is dependent on how well the scanner was programmed. The goal is to stop any operations the malware may attempt on the system before they occur, including activities which might exploit bugs or trigger unexpected operating system behavior.
Regin (malware)
Regin (also known as Prax or QWERTY) is a sophisticated malware and hacking toolkit used by United States' National Security Agency (NSA) and its British counterpart, the Government Communications Headquarters (GCHQ).
It was first publicly revealed by Kaspersky Lab, Symantec, and The Intercept in November 2014. The malware targets specific users of Microsoft Windows-based computers and has been linked to the US intelligence gathering agency NSA and its British counterpart, the GCHQ. "The Intercept" provided samples of Regin for download including malware discovered at Belgian telecommunications provider, Belgacom. Kaspersky Lab says it first became aware of Regin in spring 2012, but that some of the earliest samples date from 2003. (The name Regin is first found on the VirusTotal website on 9 March 2011.) Among computers infected worldwide by Regin, 28 percent were in Russia, 24 percent in Saudi Arabia, 9 percent each in Mexico and Ireland, and 5 percent in each of India, Afghanistan, Iran, Belgium, Austria and Pakistan. Kaspersky Lab have recently discovered multiple attack vectors used. USB, & BIOS modification allows the bulk of malware to be injected through ports 1,2,3 & 5. Many extra services & processes are visible to the victim. The 'back room' of the creators finds collisions in SHA2 message digests, suggesting a lot of CPU time is taken up. If the virus-software updates slightly altered updates (per user e.g. 256 bytes of random data), collisions for every user would have to be carried out. Kaspersky has said the malware's main victims are private individuals, small businesses and telecom companies. Regin has been compared to Stuxnet and is thought to have been developed by "well-resourced teams of developers", possibly a Western government, as a targeted multi-purpose data collection tool.