Office (OOXML) / .XLSX malware analysis — malicious · db53f42e13d2685b

MALICIOUS

Office (OOXML) / .XLSX

254.6 KB Created: 2021-04-13 11:33:03 UTC Authoring application: Microsoft Excel 16.0300

MD5: dc37192b5c4c8c4f94c73c18ce5e3829 SHA-1: 0aa6bb11a11dade2269d90b2781ed0a517362012 SHA-256: db53f42e13d2685bd34dbc5c79fad637c9344e72e210ca05504420874e98c2a6

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. While the macro content is truncated, the presence of such macros strongly suggests an intent to download and execute a secondary payload. The specific macro sheet name 'xlm_sheet_00.bin' is included as an IOC.

Heuristics 1

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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `f168b7a9fa9f7959605a73361e374bcbd8300b635752bf892d907702657526ba`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	2585 bytes

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