Office (OOXML) / .XLSX malware analysis — malicious · 58f040bb962ec7a8

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 9b1841478cf14f208ef7c823fa061cdf SHA-1: f633213296e1aef2a789fc7189c75871338c7b0e SHA-256: 58f040bb962ec7a88bda7d9b4f521ed9116fd4478d6fb98b5513912fadec716f

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 heavily truncated and obfuscated, the presence of such macros strongly suggests an intent to execute arbitrary commands. This is a common technique for downloading and executing further stages of malware. Without more readable script content, the specific payload and delivery mechanism cannot be determined.

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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