Office (OOXML) / .XLSX malware analysis — malicious · b2da2f63d450d9c0

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 9997974fcee8f8b4ad920ec1a75a2004 SHA-1: f61aecd149665461dbe23451c2a72371b830a0be SHA-256: b2da2f63d450d9c0d695461147139ede56ad5baaa5f07da721383d07520541ec

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing embedded Excel 4.0 macros. The macros contain a WMIC command to execute 'mshta' with a specific file path, 'C:\ProgramData\excel.rtf'. This indicates the macro's purpose is to download and execute a second-stage payload from that location. The file type and the presence of Excel 4.0 macros strongly suggest a macro-based delivery mechanism.

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` `a22c1898ee41ede89e97fa748867ff549e75b06ebc2113e631740af3acee6b38`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	158556 bytes

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