Office (OOXML) / .XLSX malware analysis — malicious · aa0d6b61537c561d

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: de332f199ce42ca6d4a0c906106d628d SHA-1: af2d7b536ef5872ecba07023e6b4a12828bc3b35 SHA-256: aa0d6b61537c561db7ae2a5ea9031bb5d53ee8fcc492d07b9fc32cd5d01d3edb

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.003 Windows Command Shell

The file is an Excel 4.0 macro sheet, which is a strong indicator of malicious intent. The embedded macro uses 'wmic process call create' to execute a file named 'excel.rtf' located in 'C:\ProgramData\'. This suggests a downloader or dropper functionality, aiming to execute a second-stage payload disguised as a legitimate document.

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` `b736467d6640a4d8eaeef6d08fdd7655b90bd755154df8b44958b9fc119c4978`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	61185 bytes

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