Office (OOXML) / .XLSX malware analysis — malicious · 3dd0729627f26c64

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 5381440935d774635cd12a46edbf94ff SHA-1: f4fe40b0590483140c36c7fd5a4d64e9eab1a250 SHA-256: 3dd0729627f26c644f073aa160662dcbe114d6d78874ae7629d1894d6148bf42

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. While the macro content is heavily truncated and obfuscated, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary commands. This is a common technique for downloading and executing further malicious payloads. Without more readable script content or extracted URLs, the specific family and IOCs remain unknown.

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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