Class: Trojan
A malicious program designed to electronically spy on the user’s activities (intercept keyboard input, take screenshots, capture a list of active applications, etc.). The collected information is sent to the cybercriminal by various means, including email, FTP, and HTTP (by sending data in a request).Read more
Platform: Win32
Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.Family: Trojan.Win32.Refroso
No family descriptionExamples
88EA6C4D0853CEBFB35AD1D524E13FFC60A06ABAEB3E1B134D9B28F75B41A6F1
3824AB459F4EB35D07E72B6B31CBDFCF
B08C6BDD89803CF2C8ECC15E2DFF3AB1
DACE550E8FB59C67FEFEC7A984D3843C
Tactics and Techniques: Mitre*
TA0003
Persistence
The adversary is trying to maintain their foothold.
Persistence consists of techniques that adversaries use to keep access to systems across restarts, changed credentials, and other interruptions that could cut off their access. Techniques used for persistence include any access, action, or configuration changes that let them maintain their foothold on systems, such as replacing or hijacking legitimate code or adding startup code.
Persistence consists of techniques that adversaries use to keep access to systems across restarts, changed credentials, and other interruptions that could cut off their access. Techniques used for persistence include any access, action, or configuration changes that let them maintain their foothold on systems, such as replacing or hijacking legitimate code or adding startup code.
T1546.002
Event Triggered Execution: Screensaver
Adversaries may establish persistence by executing malicious content triggered by user inactivity. Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension.(Citation: Wikipedia Screensaver) The Windows screensaver application scrnsave.scr is located in
The following screensaver settings are stored in the Registry (
*
*
*
*
Adversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity.(Citation: ESET Gazer Aug 2017)
C:\Windows\System32\, and C:\Windows\sysWOW64\ on 64-bit Windows systems, along with screensavers included with base Windows installations.The following screensaver settings are stored in the Registry (
HKCU\Control Panel\Desktop\) and could be manipulated to achieve persistence:*
SCRNSAVE.exe - set to malicious PE path*
ScreenSaveActive - set to '1' to enable the screensaver*
ScreenSaverIsSecure - set to '0' to not require a password to unlock*
ScreenSaveTimeout - sets user inactivity timeout before screensaver is executedAdversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity.(Citation: ESET Gazer Aug 2017)
TA0004
Privilege Escalation
The adversary is trying to gain higher-level permissions.
Privilege Escalation consists of techniques that adversaries use to gain higher-level permissions on a system or network. Adversaries can often enter and explore a network with unprivileged access but require elevated permissions to follow through on their objectives. Common approaches are to take advantage of system weaknesses, misconfigurations, and vulnerabilities. Examples of elevated access include:
* SYSTEM/root level
* local administrator
* user account with admin-like access
* user accounts with access to specific system or perform specific function
These techniques often overlap with Persistence techniques, as OS features that let an adversary persist can execute in an elevated context.
Privilege Escalation consists of techniques that adversaries use to gain higher-level permissions on a system or network. Adversaries can often enter and explore a network with unprivileged access but require elevated permissions to follow through on their objectives. Common approaches are to take advantage of system weaknesses, misconfigurations, and vulnerabilities. Examples of elevated access include:
* SYSTEM/root level
* local administrator
* user account with admin-like access
* user accounts with access to specific system or perform specific function
These techniques often overlap with Persistence techniques, as OS features that let an adversary persist can execute in an elevated context.
T1546.002
Event Triggered Execution: Screensaver
Adversaries may establish persistence by executing malicious content triggered by user inactivity. Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension.(Citation: Wikipedia Screensaver) The Windows screensaver application scrnsave.scr is located in
The following screensaver settings are stored in the Registry (
*
*
*
*
Adversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity.(Citation: ESET Gazer Aug 2017)
C:\Windows\System32\, and C:\Windows\sysWOW64\ on 64-bit Windows systems, along with screensavers included with base Windows installations.The following screensaver settings are stored in the Registry (
HKCU\Control Panel\Desktop\) and could be manipulated to achieve persistence:*
SCRNSAVE.exe - set to malicious PE path*
ScreenSaveActive - set to '1' to enable the screensaver*
ScreenSaverIsSecure - set to '0' to not require a password to unlock*
ScreenSaveTimeout - sets user inactivity timeout before screensaver is executedAdversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity.(Citation: ESET Gazer Aug 2017)
* © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.