Office (OOXML) / .XLSX malware analysis — malicious · 225dfdef02b4056b

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: c510940dd043a3b3d79ae1d9e87fcdfb SHA-1: 41cfd203407e10dd4b6078f53a2f5178821d48a6 SHA-256: 225dfdef02b4056bee455131660624e873b51687956a7d564746dd597772fa27

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Execution

The critical heuristic firing indicates the presence of Excel 4.0 macros within an XLSX file. These macros are known to be used for executing arbitrary commands, which is a common technique for initial access or downloading and executing further stages of malware. No specific IOCs were extracted due to the truncated nature of the script.

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` `aa40f33588f1f4e6b7458a87928ca9a9642289c1d6cc027b93494a3c15317032`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	230176 bytes

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