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

Static analysis result for SHA-256 49692fdf5cb46163…

MALICIOUS

Office (OOXML) / .XLSM

24.9 KB Created: 2021-03-11 11:00:14 UTC Authoring application: Microsoft Excel 16.0300
MD5: eb2e387236ea788411dc432961e276cf SHA-1: ba9cd7126e648819bbf14e8e557a6afc9afbff22 SHA-256: 49692fdf5cb461635452184efd19b1801b828342d062d19497437c4b8d2e044b
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, CALL, and EXEC, which are commonly used to download and execute arbitrary code. The presence of an Auto_Open defined name further suggests that these macros are designed to run automatically upon opening the document. 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
8aba8378940e03e22939707524dc2ed74933126a314979fa109b559ad11d33b2		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 19993 bytes

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