Office (OOXML) / .XLSM malware analysis — malicious · 32b25536a8d4a69b

MALICIOUS

Office (OOXML) / .XLSM

266.6 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: f36e8e47e372b2a13c3cefe3f0811639 SHA-1: 1c950cb74285f76c74a0be15227d0768482522ae SHA-256: 32b25536a8d4a69b50e2a07589dcd3d087e0cf6fade720a60c5ccf4aeba00039

190 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell

The sample is an Excel 4.0 macro sheet that leverages dangerous functions like EXEC to download and execute a payload. The macro reconstructs the path 'C:\ProgramData\tzcXqP.sct' and likely writes and executes a script from this location. This indicates a downloader or dropper functionality.

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.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `cc518a1fde7954fe210f0717d6367a667982d4b49aa2ab157b159b36e6fbbd42`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	843910 bytes

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