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

Static analysis result for SHA-256 3e206e58c06b9081…

MALICIOUS

Office (OLE) / .XLSX

153.0 KB Created: 2020-04-23 12:26:24 Authoring application: Microsoft Excel
MD5: c107bd822e1a0eabf2e72f626f707400 SHA-1: 558e0e3ad162a9a0d66cda57a33be8cd1bbe0dcc SHA-256: 3e206e58c06b908139e1d2b067e839e10cec26be4084be710b5544a2ef6ce745
100 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an encrypted Excel 4.0 macro sheet, indicated by the OLE_XLM_ENCRYPTED_MACROSHEET heuristic. The presence of an AUTOOPEN macro suggests automatic execution upon opening. While no specific document body content or scripts were extracted, the heuristics strongly indicate a malicious macro-based execution. The encrypted nature and the use of older Excel macro technology point towards a downloader or initial access mechanism.

Heuristics 3

  • Encrypted Excel 4.0 macro sheet high OLE_XLM_ENCRYPTED_MACROSHEET
    Workbook contains an Excel 4.0 macro sheet and BIFF FILEPASS encryption. Password-protected XLM macro sheets, especially the default Excel password path, are a common malware evasion pattern because static formula extraction may fail until the workbook is decrypted.
  • OLE metadata lists many Excel 4.0 macro sheets high OLE_XLM_DOCPROPS_MACROSHEET_INVENTORY
    Workbook contains a BIFF Excel 4.0 macro-sheet marker and its clear OLE DocumentSummaryInformation stream lists many MacroN sheet titles. This is a useful static signal when FILEPASS encryption prevents formula extraction from the workbook stream.
  • 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.

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