Aliser
Table of Contents
Overview
Aliser (cataloged across antivirus vendors and historical academic research under classifications including Win32/Aliser, Virus:Win32/Aliser, and Aliser.7825) is a classic polymorphic Windows PE file infector and parasitic trojan active since 2004. Engineered to achieve deep system compromise and self-preservation, Aliser scans local fixed disks and accessible network shares for valid Portable Executable (PE) files. When target executables are discovered, Aliser appends its encrypted polymorphic body to the final section of the binary, patches the entry point to divert execution flow through its decryption routine, and preserves the original host code to avoid immediate user detection. Additionally, Aliser drops auxiliary backdoor utilities into system directories, modifies registry boot values, and attempts to suppress local antivirus monitors.
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: Virus:Win32/Aliser.A · Aliser.7825
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1027 · T1547.001 · T1082 · T1105
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- 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-BDA | Binary De-obfuscation & Unpacking | Analyze | T1027 | Utilize memory dump scanners and entropy inspection to unpack encrypted stagers during process creation. |
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_ALISER_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Aliser"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "aliser" ascii wide nocase
$s2 = "win32/aliser" ascii wide nocase
$s3 = "virus:win32/aliser" ascii wide nocase
$s4 = "aliser.7825" ascii wide nocase
$s5 = "virus.win32.aliser" ascii wide nocase
$s6 = "win32.aliser.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 - Aliser (File Infector) Execution & Triage
id: 10a76a8c-aecc-55c0-81ff-ba82835e1919
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Aliser 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/aliser
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-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.file-infector
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1027
- attack.t1547_001
- attack.t1082
- attack.t1105
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_ALISER_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Aliser 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 = "aliser" 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
- Dr.Web Virus Description - Win32.Aliser
- Search "aliser" on VirusTotal (External Analysis)
- Search "aliser" on Any.Run (Sandbox Sandbox)
- Search "aliser" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Virus:Win32/Aliser?
Aliser is a classic polymorphic Windows PE file infector that parasitically infects executables on local and shared drives.
How does Aliser infect clean Windows executable files?
It appends its polymorphic code to target PE sections and redirects the Original Entry Point (OEP) to its decryptor.
Does Aliser propagate across local network shares?
Yes, Aliser enumerates mapped and accessible network shares to infect clean binaries across organizational subnets.
Why is Aliser designated as polymorphic?
Its decryption engine mutates with each infection iteration, changing its cryptographic keys and code structure.
How can systems infected with Aliser be disinfected?
Use a specialized bootable antivirus rescue disk to repair infected PE files and restore modified system executables.
How do I remove Aliser from Windows?
Manual removal of Aliser 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.
What are the main symptoms of a Aliser infection?
Symptoms of Aliser 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 File_Infectors
Want to prevent Aliser and similar threats from compromising your organization? Read our comprehensive defensive guide: Think You've Been Hacked? What To Do First.
📣 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/aliser.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.