Office (OOXML) / .XLSX malware analysis — malicious · e37d999ecef1924d

MALICIOUS

Office (OOXML) / .XLSX

50.4 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 25ee9e78ef4c4065c6855fbbcbf1aba5 SHA-1: 82687fda1dfc82f7d33cee852f66629584ee35e4 SHA-256: e37d999ecef1924d223fba6513512a2bbe05577705698b79b7f5de1c4d1e3c6f

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing an Excel 4.0 macro sheet, which is a known technique for executing malicious code. The macro sheet contains a path that appears to be an attempt to establish a malicious directory, likely for staging further payloads. The macro itself is heavily obfuscated, but the presence of the macro sheet and the suspicious path strongly indicate a downloader or initial execution stage.

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` `3dc387b6c9cb6c831ba1bbf40f62f7906d0c38b37bddb9bd8262c1ed650be6b0`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	3104 bytes

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