Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 45badf86f288a710…

MALICIOUS

Office (OOXML)

12.3 KB Created: 2021-07-01 19:00:42 UTC Authoring application: Microsoft Excel 16.0300
MD5: d1f315a82375ebc688dfb83a19c657e7 SHA-1: 4129f6c09e085ab355221c1f0a003de9519420fb SHA-256: 45badf86f288a7103e11e120d428361b61740952fe3dcc495ff10efbe2c7b2b1
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel workbook containing Excel 4.0 macros. Heuristics indicate the use of dangerous functions such as RETURN, WORKBOOK.HIDE, RUN, and GOTO, which are commonly used to execute arbitrary code and download payloads. The presence of these functions suggests the macro is designed to execute a second-stage payload, likely by leveraging the CALL or EXEC functions to interact with the operating system.

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: RETURN, WORKBOOK.HIDE, RUN, GOTO 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 (veryHidden) 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
    • 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
f081546689eec3dbfc9b498d7de9d322925c0033529f655b77643b258aa5ca25		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 10907 bytes

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