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

Static analysis result for SHA-256 3dfe528541d39836…

MALICIOUS

Office (OOXML) / .XLSM

104.6 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: a73f0003414a27259152efd5c2b237db SHA-1: aea8f1409dca44862693b04f9d50acb7a9673cfa SHA-256: 3dfe528541d398363ef273877d6161f5388feaaa3f0a7998542d20d8daee01fd
180 Risk Score

Malware Insights

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

The sample is an Excel macro-enabled spreadsheet (XLSM) containing Excel 4.0 macros. Heuristics indicate the use of dangerous XLM functions like CALL and EXEC, which are commonly used to download and execute payloads. The document body contains a URL that is likely the source of the payload. The macros likely establish persistence or download a second-stage payload.

Heuristics 4

  • Excel 4.0 macro sheet (3 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: CALL, HALT, EXEC 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.microsoft.com/office/excel/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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
5510799d9ad0e4d658960787ca401f37cfbe76b7e10a30c94b48daf8ffa996b3		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 38898 bytes
xlm_sheet_01.xml
7dd36ec19fbdc7642907b5eeb35d011f614bb08e3c70b3dc8475f6881c45a5db		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1025 bytes
xlm_sheet_02.xml
ff98d744c629bca45cd31121bc039e587be3dd5fedc3ed34476b4149a5cb101b		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 210362 bytes

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