This detection identifies potential adversary activity involving malicious PureBasic DLLs that may indicate early-stage lateral movement or code injection attempts within the environment. A proactive hunt is essential to uncover these specific artifacts before they escalate into broader compromises, ensuring timely analysis of their behavior and origin in Azure Sentinel.
rule PureBasicDLLNeilHodgson
{
meta:
author="malware-lu"
strings:
$a0 = { 83 7C 24 08 01 75 ?? 8B 44 24 04 A3 [3] 10 E8 }
condition:
$a0 at pe.entry_point
}
This YARA rule can be deployed in the following contexts:
This rule contains 1 string patterns in its detection logic.
Here are 5 specific false positive scenarios for the PureBasicDLLNeilHodgson detection rule, along with targeted filters and exclusions:
Scenario: Internal DevOps Build Pipeline Execution
PureBasic.dll into memory to process source files, triggering the YARA rule due to the presence of the specific DLL signature.jenkins-agent.exe, gitlab-runner.exe, or msbuild.exe. Additionally, filter out events occurring within the defined build server IP range (e.g., 10.20.30.0/24) during maintenance windows (01:00–05:00).Scenario: Legacy Point-of-Sale (POS) System Updates
PureBasic.dll library. This activity is often flagged as suspicious because it involves dynamic DLL loading on endpoint machines that are not typically associated with development tools.C:\Program Files\RetailPOS\Core\pos_app.exe. Furthermore, add a filter to ignore alerts where the command line contains keywords like --sync-db or --receipt-gen, which are standard operational flags.Scenario: Scheduled Inventory Management Job