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

Static analysis result for SHA-256 639f61b93ebc1163…

MALICIOUS

Office (OOXML) / .XLSM

30.6 KB Created: 2021-03-16 08:29:09 UTC Authoring application: Microsoft Excel 16.0300
MD5: 8552e8721e0b222abd564304603f0266 SHA-1: dd8754d024887b9c1ef13eacb500deccbb44129b SHA-256: 639f61b93ebc1163a5f26ca89ec46c679e902d2f741d6bcb05d09a2074c1945e
90 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an XLSM document containing VBA macros and an Excel 4.0 macro sheet, indicating it's designed to execute code upon opening. The presence of hidden sheets further suggests an attempt to conceal malicious activity. While no specific URLs or executable payloads were directly extracted, the combination of macro types strongly points to a macro-based attack pattern.

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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 2 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • 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
macros.bas
d15e850b0e3ba80973e1af068bcc8b60341282086d9d7550626d277c9cef34d0		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2509 bytes
vbaProject_00.bin
f817eb5de77bf218caf1dd21fbb6f71c498ea00c792f806d349616310af0b83e		 vba-project OOXML VBA project: xl/vbaProject.bin 23040 bytes
xlm_sheet_00.xml
c77998eae21f87e28e77a0b0752a67d2a6486bd14af15ddec5704a6fbd8a0b74		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 815 bytes

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