ExtraHop named a Leader in the 2025 Forrester Wave™: Network Analysis And Visibility Solutions

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DETECTION OVERVIEW

Malicious User Agent

Risk Factors

A user-agent string that appears in HTTP and other protocol headers can identify software running on a client. Certain types of malware that initiate post-compromise C&C communication over HTTP can be identified by a user agent (UA). Through persistent C&C communication, an attacker can remotely control a device and gain an entry point for further attacks on the network.

Category

Command-and-Control
Detection diagram
Next in Command-and-Control: Merlin C&C HTTP Connection

Attack Background

Malware can maintain communication between a victim and an attacker-controlled C&C server by sending periodic requests for instructions. The C&C server responds with tasks such as "sleep" or "run command".

C&C traffic exchanged over HTTP might include user-agent strings that can identify certain types of malware. For example, the Trickbot malware exfiltrates data to a C&C server by sending an HTTP POST request from the victim with a specific UA and exfiltrated data in the payload.

Mitigation Options

Quarantine devices to check for indicators of compromise, such as malware
Implement network segmentation, security zones, and firewall policies that limit how devices can communicate

MITRE ATT&CK ID

Associated content

Announcing The Forrester Wave™: Network Analysis And Visibility Solutions, Q4 2025

Network analysis and visibility solutions remain underrepresented in enterprises. Find out why in this preview of a new Wave report.

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ExtraHop® Named a Leader in First-Ever Gartner® Magic Quadrant™ for Network Detection and Response — ExtraHop

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News

Detections

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Docs

The 2025 ExtraHop Global Threat Landscape Report: The Alarming Reality of Threat Actor Dwell Time and Deeper Network Access — ExtraHop

This analysis exposes the critical link between an organization's lack of internal visibility and the escalating cost of compromise, demanding an urgent re-evaluation of how core business assets are protected.

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ExtraHop RevealX MITRE ATT&CK Coverage 2024 — ExtraHop

Learn why you need to be wary of the claims certain network detection and response providers make about their coverage against the MITRE ATT&CK framework.

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MITRE ATT&CK - Network Detection & Response with RevealX — ExtraHop

Learn how NDR from RevealX helps security teams detect and investigate more adversary TTPs in the MITRE ATT&CK framework than rule-based tools.

External
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