Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 b83287a55a92ee2b…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:45:14 Authoring application: Microsoft Excel
MD5: 9ce50f2d5b72fa3dc2f9b08aa2d9f896 SHA-1: 1f8e4e67caba41095fbbf834542cdcc94625cd67 SHA-256: b83287a55a92ee2b0708ee24454eabaa0f599447f2266710e0b2bfe59f0e737c
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that utilizes dangerous functions, specifically the RUN function. This strongly suggests the macro is designed to execute arbitrary commands. The presence of the Auto_Open defined name further confirms this execution path. The macro sheet itself is named 'sfdPnr', and the Auto_Open function is explicitly identified. The primary intent is to download and execute a second-stage payload.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e5fbf1f93883e9735102f4baf28cda6cf922302f16344633454610727121afe8		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6515 bytes

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