Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 05cf3a5a236ef847…

MALICIOUS

Office (OOXML) / .XLSM

102.2 KB Created: 2021-08-19 14:03:52 UTC Authoring application: Microsoft Excel 15.0300
MD5: 0c326ad3ee910df1c4cda95844c8af68 SHA-1: 24471551bf75b3f805adc41d358fd5928241e2fc SHA-256: 05cf3a5a236ef847503fdc9bcb14ec4302a1f317e43639d7f012a2b8f6f68426
342 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is an XLSM file containing a Workbook_Open VBA macro. This macro executes a command that downloads a batch file from 'http://3.112.243.28/tun/7705221205.bat' using certutil.exe and then executes the downloaded file as 'Rklkmvrvm.exe.exe'. This indicates a downloader or dropper functionality.

Heuristics 8

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
  • ClamAV: Xls.Dropper.EPPlus-9802867-2 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.EPPlus-9802867-2
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://3.112.243.28/tun/7705221205.bat

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
ce5b756780cfc78f5d56d0e2edaea82bef6f52e0c34ef4d7cd8ff3fbaeae8f13		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1091 bytes
vbaProject_00.bin
4c2cf69ed57f5e85c3e15908481dbee5117a942b55ce1451bb5a196506ded3b9		 vba-project OOXML VBA project: xl/vbaProject.bin 5632 bytes
Detection
ClamAV: Xls.Dropper.EPPlus-9802867-2
Obfuscation or payload: unlikely

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