Office (OOXML) / .XLSX malware analysis — malicious · cfd08fb28c11ec1f

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 2d9d4c6eea61cc2141435f3dba81f073 SHA-1: c68d564958e35101167032700aaf22a7a144b33a SHA-256: cfd08fb28c11ec1fdfe9efb6f9ec334d4ee9758005c65d331081bbef39f31122

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. These macros are capable of executing arbitrary commands, which is a common technique for initial access or payload delivery. However, the macro content is heavily truncated and obfuscated, preventing a more detailed analysis of its specific actions or the reconstruction of any URLs or commands.

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` `5683a2819239d418a79386754da395ea1e0d613192c4f1650b5c7b0308799e19`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	299437 bytes

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