Favadd

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Bookmark Injection: Favadd aggressively modifies the configuration files and registry keys associated with major web browsers (Internet Explorer, Firefox, older versions of Chrome). It adds dozens of bookmarks leading to online casinos, fake tech support pages, and aggressive affiliate marketing sites.
• Browser Hijacking: The malware often alters the browser's default homepage, new tab page, and default search engine provider to force the user's web traffic through a monetization gateway controlled by the adware authors.
• Persistence: To prevent the user from simply deleting the bookmarks, Favadd often utilizes a background service or a persistent browser helper object (BHO) that automatically restores the malicious bookmarks upon every system reboot or browser launch.

Threat Assessment

Remediation and Eradication

• Application Removal: The first step is to identify and uninstall the core adware application via the Windows Control Panel, looking for recently installed, suspicious "free" utilities or toolbars.
• Browser Reset: Because Favadd deeply alters browser configurations, the most effective remediation is a complete reset of all installed web browsers to their factory default settings, which automatically clears malicious extensions, BHOs, and injected bookmarks.
• Anti-Malware Sweep: Run a comprehensive scan using a reputable anti-malware solution specifically tuned to detect and remove Potentially Unwanted Programs (PUPs) and lingering registry keys left behind by the adware.

Known aliases

Threat reports may refer to this family under multiple names:

• Adware.Favadd
• Trojan.Favadd
• PUP.Favadd

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:

• T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.

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_FAVADD_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Favadd"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "favadd" ascii wide nocase
        $s2 = "adware.favadd" ascii wide nocase
        $s3 = "trojan.favadd" ascii wide nocase
        $s4 = "pup.favadd" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Favadd (Trojan) Execution & Triage
id: 4eb2b488-843d-5c37-987b-d9404a794e91
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Favadd 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/favadd
- 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.t1185
- attack.t1176
- attack.t1546_015
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_FAVADD_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Favadd 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 = "favadd" 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. Sever network connectivity for the flagged endpoint to terminate persistent command-and-control (C2) communication channels and stop Favadd from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Favadd into legitimate system processes such as explorer.exe or svchost.exe.
3. Audit Windows Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) and Task Scheduler entries to locate and purge Favadd persistence hooks.
4. Deploy updated enterprise EDR detection signatures and conduct an out-of-band endpoint scan to isolate dropped binaries and staged payloads.
5. Rotate all credentials, domain user passwords, and session cookies active on the system during the Favadd execution timeframe.

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 simply because an antivirus tool removed the initial Favadd dropper; always verify that secondary payloads and persistence hooks have been eradicated.
2. Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Favadd until memory triage is complete.
3. Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Ggpass
• Luminorat
• Genericrxge
• Mirc
• Agen
• Tpyn
• Ausiv
• Frethog

Machine-readable

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