Hiding Malicious Data or Code within Files (CAPEC-636)
Files on various operating systems can have a complex format which allows for the storage of other data, in addition to its contents. Often this is metadata about the file, such as a cached thumbnail for an image file. Unless utilities are invoked in a particular way, this data is not visible during the normal use of the file. It is possible for an attacker to store malicious data or code using these facilities, which would be difficult to discover.
Infected Software (CAPEC-442)
An adversary adds malicious logic, often in the form of a computer virus, to otherwise benign software. This logic is often hidden from the user of the software and works behind the scenes to achieve negative impacts. Many times, the malicious logic is inserted into empty space between legitimate code, and is then called when the software is executed. This pattern of attack focuses on software already fielded and used in operation as opposed to software that is still under development and part of the supply chain.
Embed Virus into DLL (CAPEC-448)
An adversary tampers with a DLL and embeds a computer virus into gaps between legitimate machine instructions. These gaps may be the result of compiler optimizations that pad memory blocks for performance gains. The embedded virus then attempts to infect any machine which interfaces with the product, and possibly steal private data or eavesdrop.