EQGRP Toolset Firewall - file BBALL_E28F6-2201.exe

Hunt Hypothesis

The detection identifies potential adversary use of the BBALL_E28F6-2201.exe file, which is associated with the EQGRP toolset, often used for network reconnaissance and firewall manipulation. SOC teams should proactively hunt for this behavior to identify early-stage network infiltration attempts that may evade traditional detection methods.

YARA Rule

rule EQGRP_BBALL 
{

    meta:
        description = "EQGRP Toolset Firewall - file BBALL_E28F6-2201.exe"
        author = "Florian Roth"
        reference = "Research"
        date = "2016-08-16"
        hash1 = "498fc9f20b938b8111adfa3ca215325f265a08092eefd5300c4168876deb7bf6"

    strings:
        $s1 = "Components/Modules/BiosModule/Implant/E28F6/../e28f640j3_asm.S" fullword ascii
        $s2 = ".got_loader" fullword ascii
        $s3 = "handler_readBIOS" fullword ascii
        $s4 = "cmosReadByte" fullword ascii
        $s5 = "KEEPGOING" fullword ascii
        $s6 = "checksumAreaConfirmed.0" fullword ascii
        $s7 = "writeSpeedPlow.c" fullword ascii

    condition:
        ( uint16(0) == 0x457f and filesize < 40KB and 4 of ($s*) ) or ( all of them )
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 7 string patterns in its detection logic.

References

• Research
• Source Rule

False Positive Guidance

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate system maintenance task uses the BBALL_E28F6-2201.exe file as part of a scheduled job to perform disk cleanup or registry optimization.
  Filter/Exclusion: Check for the presence of a scheduled task with a known name (e.g., CleanupTask) and verify the file path is within a system directory like C:\Windows\Temp or C:\Windows\System32.

• Scenario: Antivirus or Endpoint Protection Scan
  Description: A security tool such as Kaspersky, Bitdefender, or Microsoft Defender may use a similar-named executable during a full system scan.
  Filter/Exclusion: Include a condition to check the process parent or command line for known antivirus processes (e.g., msdefender.exe, kavsvc.exe) or verify the file is in a protected directory like C:\Program Files\Kaspersky\.

• Scenario: Software Update or Patch Deployment
  Description: A legitimate software update or patch deployment tool (e.g., Microsoft Update, Chocolatey, or WSUS) may use a similar-named executable during installation.
  Filter/Exclusion: Filter by the presence of update-related command-line arguments (e.g., /quiet, /norestart) or check the file path against known update directories (e.g., C:\Windows\Temp\UpdateInstaller).

• Scenario: User-Initiated File Execution for Debugging
  Description: A developer or admin may run BBALL_E28F6-2201.exe manually for debugging purposes, especially if it’s a custom or third-party tool.
  Filter/Exclusion: Include a condition to check the user context (e.g., User = Administrator) and