Installing Malicious Software

The subject deploys destructive malware; software designed to irreversibly damage systems, erase data, or disrupt operational availability. Unlike ransomware, which encrypts files to extort payment, destructive malware is deployed with the explicit intent to delete, corrupt, or disable systems and assets without recovery. Its objective is disruption or sabotage, not necessarily for direct financial gain.

This behavior may include:

• Wiper malware (e.g. HermeticWiper, WhisperGate, ZeroCleare)
• Logic bombs or time-triggered deletion scripts
• Bootloader overwrite tools or UEFI tampering utilities
• Mass delete or format scripts (format, cipher /w, del /s /q, rm -rf)
• Data corruption utilities (e.g. file rewriters, header corruptors)
• Credential/system-wide lockout scripts (e.g. disabling accounts, resetting passwords en masse)

Insiders may deploy destructive malware as an act of retaliation (e.g. prior to departure), sabotage (e.g. to disrupt an investigation or competitor), or under coercion. Detonation may be manual or scheduled, and in some cases the malware is disguised as routine tooling to delay detection.

Destructive deployment is high-severity and often coincides with forensic tampering or precursor access based infringements (e.g. file enumeration or backup deletion).

The subject deploys credential-harvesting malware (commonly referred to as an infostealer) to extract sensitive authentication material or session artifacts from systems under their control. These payloads are typically configured to capture data from browser credential stores (e.g., Login Data SQLite databases in Chromium-based browsers), password vaults (e.g., KeePass, 1Password), clipboard buffers, Windows Credential Manager, or the Local Security Authority Subsystem Service (LSASS) memory space.

Infostealers may be executed directly via compiled binaries, staged through malicious document macros, or loaded reflectively into memory using PowerShell, .NET assemblies, or process hollowing techniques. Some variants are fileless and reside entirely in memory, while others create persistence via registry keys (e.g., HKCU\Software\Microsoft\Windows\CurrentVersion\Run) or scheduled tasks.

While often associated with external threat actors, insider deployment of infostealers allows subjects to bypass authentication safeguards, impersonate peers, or exfiltrate internal tokens for later use or sale. In cases where data is not immediately exfiltrated, local staging (e.g., in %AppData%, %Temp%, or encrypted containers) may indicate an intent to transfer data offline or deliver it via alternate channels.

The subject deploys software designed to record keystrokes entered on an endpoint to capture credentials, sensitive communications, internal documentation, or intellectual property. Keyloggers may be introduced as standalone binaries, embedded within otherwise legitimate tools, or configured through dual-use frameworks (e.g. C++ dropper with keylogging module). In insider scenarios, the deployment is typically local and deliberate, leveraging the subject’s physical access or assigned privileges to bypass existing controls.

Keyloggers operate in one of several modes:

• Kernel-based: Install drivers or hook low-level keyboard input APIs (e.g. Kbdclass.sys) to intercept inputs pre-OS.
• User-mode: Hook Windows APIs (SetWindowsHookEx, GetAsyncKeyState, GetForegroundWindow) to log input tied to active processes or windows.
• Form grabbers: Intercept browser or GUI form submissions, often bypassing SSL/TLS encryption by logging data pre-submission.
• Clipboard and screen scrapers: Supplement keylogging with capture of copied content and screenshots for contextual awareness.

Captured data is typically stored in encrypted local files (e.g. %TEMP%, %APPDATA%, or hidden directories), periodically exfiltrated via email, FTP, HTTP POST, or external storage.

The subject deploys ransomware within the organization’s environment, resulting in the encryption, locking, or destructive alteration of organizational data, systems, or backups. Ransomware used by insiders may be obtained from public repositories, affiliate programs (e.g. RaaS platforms), or compiled independently using commodity builder kits. Unlike external actors who rely on phishing or remote exploitation, insiders often bypass perimeter controls by detonating ransomware from within trusted systems using local access.

Ransomware payloads are typically compiled as executables, occasionally obfuscated using packers or crypters to evade detection. Execution may be initiated via command-line, scheduled task, script wrapper, or automated loader. Encryption routines often target common file extensions recursively across accessible volumes, mapped drives, and cloud sync folders. In advanced deployments, the subject may disable volume shadow copies (vssadmin delete shadows) or stop backup agents (net stop) prior to detonation to increase impact.

In some insider scenarios, ransomware is executed selectively: targeting specific departments, shares, or systems, rather than broad detonation. This behavior may indicate intent to send a message, sabotage selectively, or avoid attribution. Payment demands may be issued internally, externally, or omitted entirely if disruption is the primary motive.

The subject deploys a Remote Access Tool (RAT): a software implant that provides covert, persistent remote control of an endpoint or server—enabling continued unauthorized access, monitoring, or post-employment re-entry. Unlike sanctioned remote administration platforms, RATs are deployed without organizational oversight and are often configured to obfuscate their presence, evade detection, or blend into legitimate activity.

RATs deployed by insiders may be off-the-shelf tools (e.g. njRAT, Quasar, Remcos), lightly modified open-source frameworks (e.g. Havoc, Pupy), or commercial-grade products repurposed for unsanctioned use (e.g. AnyDesk, TeamViewer in stealth mode). 

Functionality typically includes:

• Full GUI or shell access
• File system interaction
• Screenshot and webcam capture
• Credential harvesting
• Process and registry manipulation
• Optional keylogging and persistence modules

Deployment methods include manual installation, script-wrapped droppers, DLL side-loading, or execution via LOLBins (mshta, rundll32). Persistence is typically achieved through scheduled tasks, registry run keys, or disguised service installations. In some cases, the RAT may be configured to activate only during specific windows or respond to remote beacons, reducing exposure to detection.