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

Static analysis result for SHA-256 9794c95688a8455c…

MALICIOUS

Office (OOXML) / .XLSM

284.1 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 93ebbf5b027acf34dce22ffb21dcf2e3 SHA-1: 9a97d3c72af13bc7cc4732b8e2456b32b096b456 SHA-256: 9794c95688a8455c9a8e600e974789a95faacae9acfaea4c052237de0cfa7b25
190 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1059.005 Visual Basic T1204 User Execution T1059 Command and Scripting Interpreter

The sample is an XLSM file containing Excel 4.0 macros. The macros utilize dangerous functions like CALL and EXEC to write a SCT file to C:\ProgramData\JyqTBGDZEf.sct and then execute it. This indicates a downloader or dropper functionality, aiming to execute a second-stage payload.

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: FOPEN, FWRITE, FCLOSE, EXEC, 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 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
f30b035af656dbf1d80daf7d89e64fa29ddbd9e5414e6ae650252fbbfad82305		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1005817 bytes

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