Masquerading occurs when the name or location of an executable, legitimate or malicious, is manipulated or abused for the sake of evading defenses and observation. Several different variations of this technique have been observed.
One variant is for an executable to be placed in a commonly trusted directory or given the name of a legitimate, trusted program. Alternatively, the filename given may be a close approximation of legitimate programs or something innocuous. An example of this is when a common system utility or program is moved and renamed to avoid detection based on its usage.(Citation: FireEye APT10 Sept 2018) This is done to bypass tools that trust executables by relying on file name or path, as well as to deceive defenders and system administrators into thinking a file is benign by associating the name with something that is thought to be legitimate.
Adversaries may modify a binary's metadata, including such fields as icons, version, name of the product, description, and copyright, to better blend in with the environment and increase chances of deceiving a security analyst or product.(Citation: Threatexpress MetaTwin 2017)
In another variation of this technique, an adversary may use a renamed copy of a legitimate utility, such as rundll32.exe. (Citation: Endgame Masquerade Ball) An alternative case occurs when a legitimate utility is moved to a different directory and also renamed to avoid detections based on system utilities executing from non-standard paths. (Citation: F-Secure CozyDuke)
An example of abuse of trusted locations in Windows would be the <code>C:\Windows\System32</code> directory. Examples of trusted binary names that can be given to malicious binares include "explorer.exe" and "svchost.exe".
Another variation of this technique includes malicious binaries changing the name of their running process to that of a trusted or benign process, after they have been launched as opposed to before. (Citation: Remaiten)
An example of abuse of trusted locations in Linux would be the <code>/bin</code> directory. Examples of trusted binary names that can be given to malicious binaries include "rsyncd" and "dbus-inotifier". (Citation: Fysbis Palo Alto Analysis) (Citation: Fysbis Dr Web Analysis)