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

Static analysis result for SHA-256 38946bb4b35e39c3…

MALICIOUS

Office (OOXML) / .XLSM

92.6 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: e09149f5419c9de9dce1e5f79db8aa61 SHA-1: b000ac479e8e60e75db150ef477e731c7d7f85f4 SHA-256: 38946bb4b35e39c3edbf13898554e9e5643604fdf3a2d3376e464f6d89f9426d
180 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro sheet that utilizes dangerous functions like CALL and EXEC. The embedded document body contains a list of URLs, indicating the macro's purpose is to download and execute a second-stage payload from one of these locations. The use of Excel 4.0 macros and the download-and-execute pattern are common for initial access and payload delivery.

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: EXEC, HALT, CALL, FORMULA.FILL 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
b2aa95d3b3a02526f200b3d969c9988b4d5832e6c13ac8dcb3a1d9eb395b3574		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 213450 bytes

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