Staser
Table of Contents
Overview
Staser (cataloged in antimalware telemetry under signatures including Trojan:Win32/Staser, TrojanDownloader:Win32/Staser, and Trojan.Staser) is an evasive multi-stage Windows trojan loader and information-harvesting implant active since 2015. Infiltrating endpoints primarily through phishing email attachments and malicious torrent downloads, Staser functions as an initial staging loader for secondary crimeware threats. Upon execution, Staser performs environmental fingerprinting, checks for sandbox and hypervisor indicators, and creates autostart registry keys to establish persistence. It connects to remote command-and-control servers over HTTP/HTTPS, transmits host telemetry, and downloads encrypted payload files—frequently modular banking trojans, cryptocurrency miners, and ransomware—saving and executing them from temporary directories or directly into memory via process hollowing.
Known aliases
Threat reports may refer to this family under multiple names:
Family Pedigree & Lineage
Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:
Known Derivatives & Downstream Variants: Trojan:Win32/Staser.A · Trojan:Win32/Staser.B
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1059.003 · T1105 · T1055 · T1082 · T1547.001
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
- T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-PIAD | Process Injection Analysis & Detection | Detect | T1055 | Monitor cross-process thread creation (CreateRemoteThread) and asynchronous procedure calls (QueueUserAPC). |
D3-PBA | Process Spawn Analysis | Detect | T1059.003 | Inspect command-line arguments and anomalous parent-child relationships spawning from cmd.exe. |
D3-SDA | System Discovery Analysis | Detect | T1082 | Alert on rapid enumerations of systeminfo, hostname, and registry hardware trees in short intervals. |
D3-NTI | Network Traffic Inspection | Detect | T1105 | Inspect deep packet payloads for anomalous staging binaries and unauthorized egress protocols. |
D3-RPM | Registry Persistence Monitoring | Detect | T1547.001 | Audit and restrict write privileges to user and machine-level Registry Run/RunOnce keys using Endpoint Privilege Management. |
Tiered Detection Rules (Cisco CAIRN Model)
Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_STASER_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Staser"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "staser" ascii wide nocase
$s2 = "trojan:win32/staser" ascii wide nocase
$s3 = "trojandownloader:win32/staser" ascii wide nocase
$s4 = "trojan.staser" ascii wide nocase
$s5 = "win32/staser" ascii wide nocase
$s6 = "trojan:win32/staser.a" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Staser (Trojan) Execution & Triage
id: 0337e27a-f664-56b7-8d81-f973c24e9442
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Staser malware family. Detects suspicious execution from temporary user
directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/staser
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_003
- attack.t1105
- attack.t1055
- attack.t1082
- attack.t1547_001
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \cmd.exe
- \powershell.exe
- \cscript.exe
- \wscript.exe
CommandLine|contains:
- AppData\Local\Temp
- -WindowStyle Hidden
- /e:jscript
- bitsadmin /transfer
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: mediumTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_STASER_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Staser tradecraft"
tier = "T3 - Attribution Fingerprint"
confidence = "High (Confirmed Family Signature)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
// Core family identifier & heuristic payload signatures
$attrib_str = "staser" ascii wide nocase
$pe_magic = "MZ" ascii
$net_marker = "http" ascii nocase
condition:
uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}References & External Analysis
- Microsoft Defender Threat Encyclopedia - Trojan:Win32/Staser
- Trend Micro Threat Encyclopedia - Trojan.Win32.Staser
- Search "staser" on VirusTotal (External Analysis)
- Search "staser" on Any.Run (Sandbox Sandbox)
- Search "staser" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Trojan:Win32/Staser?
Staser is a multi-stage Windows trojan loader that collects system telemetry and stages secondary payloads like ransomware.
How does Staser evade security defenses?
It checks for virtual machine artifacts, uses PEB hashing for dynamic API resolution, and hollows code into svchost.exe.
What secondary payloads are deployed by Staser?
Threat actors use Staser to deliver banking trojans, password stealers, cryptocurrency miners, and ransomware.
How does Staser maintain persistence on Windows?
It creates autostart registry entries under CurrentVersion\Run and registers background scheduled tasks.
How should an enterprise respond to a Staser detection?
Isolate the endpoint, review process lineage for injected svchost.exe processes, and conduct full remediation of dropped payloads.
How do I remove the Staser Trojan from Windows?
Manual removal of Staser is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
Is Staser a virus or a Trojan?
Staser is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Staser typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Staser infection?
Symptoms of Staser can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Trojans
Want to prevent Staser and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection for Businesses.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/staser.json
Ecosystem & Interactive Environments
This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.