Oficla

Overview

Trojan:Win32/Oficla (also widely known as Sasfis) is a historically massive botnet and trojan downloader that peaked in activity between 2010 and 2012. Its primary function was to compromise endpoints and turn them into 'zombies' within the Oficla botnet. These zombies were then rented out to other cybercriminals to silently download and execute secondary payloads (`T1105`), most notoriously Fake Antivirus (Rogue software), spam bots (like Rustock), and banking trojans (like Zeus).

Understanding Oficla (Sasfis Botnet Operations)
To an end-user, an Oficla infection was usually silent, noticeable only when the secondary payload (like a screaming Fake AV pop-up) executed. For a security operations center (SOC), Oficla represents a critical breach. If Oficla is detected, the system must be considered fully compromised by multiple, unknown threat actors, as the botnet operators frequently sold access to the same machine to multiple buyers.

Execution and C2 Mechanics
Oficla was primarily distributed via massive spam campaigns (`T1566.001`), often disguised as fake delivery invoices (FedEx, UPS) containing malicious executables inside ZIP files, or via exploit kits on compromised websites. Upon execution, it injects its code into `explorer.exe` or `svchost.exe` (`T1055`) to hide its activity and establishes persistence via the Registry Run keys. It communicates with its C2 servers using HTTP POST requests, often employing a fast-flux DNS network to hide the true location of the servers. The C2 server responds with encrypted URLs pointing to the secondary payloads the bot must download and execute.

Indicators of Compromise & Impact
The primary impact is the deployment of severe secondary malware and incorporation into a criminal botnet. Host-based IoCs include EDR alerts for process injection (particularly into `explorer.exe`) and the rapid, silent downloading and execution of unknown binaries into the `%Temp%` directory. Network IoCs include a distinctive 'beaconing' pattern of HTTP POST requests containing encrypted system profiling data sent to rapidly changing, algorithmically generated domains (DGAs).

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

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.
• T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

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:

rule MALWARE_WIN_OFICLA_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Oficla"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "oficla" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Oficla (Trojan) Execution & Triage
id: 1ff866d5-9e0e-5435-85b9-a7e68f0ab562
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Oficla 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/oficla
- 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.t1547_001
- attack.t1105
- attack.t1566_001
- attack.t1055
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: medium

rule MALWARE_WIN_OFICLA_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Oficla 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 = "oficla" 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
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Immediately isolate the compromised endpoint from the network to sever its connection to the Oficla C2 infrastructure.
2. Assume the system is heavily compromised by multiple malware families; initiate a full reimaging of the machine rather than attempting cleanup.
3. Analyze DNS and proxy logs to identify the C2 domains Oficla contacted and block them enterprise-wide to prevent further botnet registration.
4. Implement email filtering rules to block executable attachments (e.g., `.exe`, `.scr` inside `.zip` files) commonly used to distribute the malware.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not assume the incident is resolved by merely deleting the initial Oficla executable; it is guaranteed that secondary payloads were downloaded.
2. Avoid trusting the integrity of the operating system after an Oficla infection; full wipe and reinstall is the only safe remediation.

References & External Analysis

• Search "oficla" on VirusTotal (External Analysis)
• Search "oficla" on Any.Run (Sandbox Sandbox)
• Search "oficla" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Sixxpack
• Dyloader
• Yakes
• Karamanak
• Ggdoor
• Delf
• Swisyn
• Genericrxbg

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/oficla.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.