Proxyagent

Overview

Executive Summary

Technical Architecture and Exploitation

• Silent Installation and Persistence: The malware installs itself as a hidden background service or injects its code into a legitimate network-facing process (like `svchost.exe`). It modifies Windows Firewall rules to allow inbound connections on a specific port chosen by the attacker.
• C2 Registration: The trojan registers the infected machine's IP address, bandwidth capacity, and open proxy port with a centralized command-and-control (C2) server. The infected machine is now part of a commercial proxy botnet (often sold on the dark web).
• Traffic Routing: The attacker routes arbitrary traffic through the infected host. This traffic may include credential stuffing attacks against other organizations, spam distribution, or illegal file sharing, all of which appear to originate from the victim's corporate network.

Threat Impact

Incident Response and Mitigation

• Network Anomaly Detection: Monitor edge firewalls for sustained, high-volume inbound and outbound traffic on non-standard ports, which is highly indicative of an active proxy relay.
• Endpoint Isolation: If a host is identified acting as a proxy, immediately isolate it from the network to halt the illicit traffic routing and prevent IP reputation damage.
• Forensic Review: A proxy trojan is rarely the only malware on a system. Conduct a full forensic review to identify the initial access vector (the dropper) and determine if other, more destructive payloads (like info-stealers) were also deployed alongside the ProxyAgent.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan.ProxyAgent
• Proxy.Botnet
• Win32/ProxyAgent

MITRE ATT&CK Techniques

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

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_PROXYAGENT_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Proxyagent"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "proxyagent" ascii wide nocase
        $s2 = "trojan.proxyagent" ascii wide nocase
        $s3 = "proxy.botnet" ascii wide nocase
        $s4 = "win32/proxyagent" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Proxyagent (Trojan) Execution & Triage
id: ec2c698f-6f3a-5b25-a9ef-61659d223e34
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Proxyagent 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/proxyagent
- 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.t1090_002
- attack.t1562_004
- attack.t1543_003
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_PROXYAGENT_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Proxyagent 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 = "proxyagent" 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 Proxyagent from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Proxyagent 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 Proxyagent 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 Proxyagent 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 Proxyagent 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 Proxyagent 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 "proxyagent" on VirusTotal (External Analysis)
• Search "proxyagent" on Any.Run (Sandbox Sandbox)
• Search "proxyagent" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Firehooker
• Wizrem
• Cool_Remote_Control
• Magala
• Aspxor
• Bubbledock
• Cashfiesta
• Messiah

Machine-readable

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