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

Static analysis result for SHA-256 1bfddead00488814…

MALICIOUS

Office (OOXML) / .XLSM

25.3 KB Created: 2021-03-11 11:11:43 UTC Authoring application: Microsoft Excel 16.0300
MD5: 7357ca13dac7f6d7e079aae8dc6235a4 SHA-1: c98eb3c6813994e36d455b9f45068632ce2e2bd6 SHA-256: 1bfddead00488814fef3164695bf64eecbe00ca539b2e5490da7fca28aefe769
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file is an XLSM document containing Excel 4.0 macros. The heuristics indicate the use of dangerous XLM formula APIs like FORMULA, which are known to be used for downloading and executing payloads. The presence of an Auto_Open defined name suggests the macros execute automatically upon opening. No specific family could be identified, and no external IOCs were extracted.

Heuristics 4

  • Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: FORMULA critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • 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://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
ce8486135d6931ed944cd4a0f9502cc5eccb262cce3ff25b8ddc381d4619da3a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 20854 bytes

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