Zenosearch

Overview

Executive Summary

Distribution and Technical Behavior

• Browser Hijacking: ZenoSearch alters the browser's default search engine, homepage, and new tab settings. All search traffic is redirected through an affiliate-linked search portal controlled by the adware operators to generate illicit ad revenue.
• Traffic Interception and Injection: The software frequently installs malicious browser extensions or a local proxy server to intercept unencrypted web traffic. It overlays legitimate websites with disruptive pop-ups, pop-unders, banner ads, and sponsored in-text hyperlinks.
• Data Harvesting: It continuously tracks the user's browsing history, search queries, and clickstreams, transmitting this telemetry to remote servers to serve highly targeted advertisements.

Risk Assessment

Mitigation and Removal Strategies

• Endpoint Scanning: Utilize a reputable enterprise-grade anti-malware solution to perform a deep system scan, targeting the ZenoSearch executables, hidden scheduled tasks, and persistent registry keys used to maintain its hold on the browser.
• Browser Remediation: Manually inspect and remove any unknown or unauthorized extensions from all installed web browsers. Perform a complete factory reset of the browsers to clear the hijacked proxy and search settings.
• Application Control: Enforce strict application whitelisting policies to prevent standard users from executing unapproved software installers that are the primary vector for this adware.

Known aliases

Threat reports may refer to this family under multiple names:

• Adware.ZenoSearch
• PUP.ZenoSearch
• BrowserModifier:Win32/ZenoSearch

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:

• T1566.002: Inspect email links for known malicious domains and use link-rewriting services for time-of-click analysis.

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_ZENOSEARCH_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Zenosearch"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "zenosearch" ascii wide nocase
        $s2 = "adware.zenosearch" ascii wide nocase
        $s3 = "pup.zenosearch" ascii wide nocase
        $s4 = "browsermodifier:win32/zenosearch" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Zenosearch (Advanced Threat) Execution & Triage
id: 0d916fc6-310e-5e22-a1bc-ea337f5aa7ba
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Zenosearch malware family. Detects proxy execution, reflective DLL loading,
  and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/zenosearch
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-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.advanced-threat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_002
- attack.t1176
- attack.t1112
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \powershell.exe
    - \cmd.exe
    - \rundll32.exe
    - \regsvr32.exe
    CommandLine|contains:
    - DownloadString
    - IEX(
    - '/s /n /u /i:'
    - sc create
    - start-process
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_ZENOSEARCH_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Zenosearch 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 = "zenosearch" 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. Enforce forensic network isolation on all suspected endpoints while maintaining an out-of-band telemetry conduit to capture live Zenosearch adversary activity.
2. Perform full memory dumps across identified staging nodes to extract memory-only implants, kernel rootkit hooks, and decrypted Zenosearch C2 infrastructure IP/domain lists.
3. Review Active Directory domain controller authentication logs for anomalous Kerberos ticket requests (Pass-the-Ticket, Golden Ticket) and unauthorized DCSync operations associated with Zenosearch.
4. Block all confirmed C2 domains, dynamic DNS endpoints, and proxy IP addresses across perimeter firewalls, proxies, and DNS security gateways.
5. Conduct an enterprise-wide sweep across surrounding subnets for secondary webshells, WMI event subscriptions, or remote execution tooling left behind by Zenosearch operators.

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

Frequently Asked Questions

Related Threats (Category: Advanced Threat)

Explore other documented threats in the same operational category:

• Smbd
• Easyspeedcheck
• Speedchecker
• Torrenteasy
• Spectorpro
• Patchupplus
• Systemcare
• Slingshot

Machine-readable

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