Office (OOXML) / .XLSX malware analysis — malicious · b6dbddefa0291fb8

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 13404d1fe15edcc425a9f6aeefd71ec4 SHA-1: 6d0c44575bd3ebe5bee46bd41952f3263207204d SHA-256: b6dbddefa0291fb8b401968e6ab25709fa8bc752b8495721f8d4407062a1c204

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The macros are likely intended to execute arbitrary commands, 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` `c2ca0c3abded6f36b4b3b779cf51a2aad0535c3a294b434bcdaef17504ae611c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	228258 bytes

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