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

Static analysis result for SHA-256 086590a4e3d21e94…

MALICIOUS

Office (OOXML) / .XLSM

113.9 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 833678392144fb4d7c3f66d9aa039f8e SHA-1: bec21dcdaa143bf0a5b4835b682767d1777d15c0 SHA-256: 086590a4e3d21e948f8b828b4117519e07a0723bb8fe554b407abd422eceed26
130 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

This Excel 4.0 macro sheet utilizes dangerous functions like FOPEN and EXEC to write a file to disk. The constructed filename is C:\ProgramData\dFOTtIhBAR.vbs. The macro also displays an alert message, likely to distract the user or indicate a failed operation. The use of these functions suggests an attempt to download and execute a secondary payload.

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.
  • Dangerous XLM formula APIs: FOPEN, FWRITE, FCLOSE, EXEC, RETURN 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.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
a3f8824590c1e3369e67d02bd16a929b2a35441d48ad89355b1b72e5c198ac5b		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5320 bytes

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