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

Static analysis result for SHA-256 8f00e5f8c6d1ab0e…

MALICIOUS

Office (OOXML) / .XLSX

24.9 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: b9964acc0bd0a0ae1e2a6927cf1a7340 SHA-1: 4fcdc594ab217121178236148ce18a5c50c01470 SHA-256: 8f00e5f8c6d1ab0ef91f4b5bc31a956e6a7f40d97d3a06acbe4c78beff7d3a6d
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

This Excel 4.0 macro-enabled document utilizes dangerous functions like FORMULA.FILL and EXEC to download a payload from multiple URLs and register it as a DLL. The script reconstructs the persistence mechanism as HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy. The embedded URLs point to potential second-stage payloads.

Heuristics 5

  • 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.FILL, EXEC, RETURN, REGISTER, RUN, HALT 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 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
21d8c550b12c2c2883ded91c83c9d0d541f76b29de305d11c828ec9bd4efd475		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 4872 bytes

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