Office (OOXML) / .XLSX malware analysis — malicious · 57f8a37b6af2a1c6

MALICIOUS

Office (OOXML) / .XLSX

109.6 KB Created: 2021-03-29 19:54:41 UTC Authoring application: Microsoft Excel 16.0300

MD5: 727ffff7c47db607b006c7bf488e3285 SHA-1: 5b321e8c576f964598e6a1b177d451d43bafd556 SHA-256: 57f8a37b6af2a1c68f212a63879226db30829bd45c11dc4ba462476f814d6975

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet. While the macro content is heavily truncated and obfuscated, the presence of such a sheet strongly suggests an attempt to execute arbitrary commands. This is a common technique for initial payload delivery or system compromise.

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` `4ba2168210d43affdc2df39a4c02216ffe17c7afee4f75dbc3d4113362e4fe4d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	96634 bytes

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