Office (OOXML) / .XLSX malware analysis — malicious · 2704310ba04a4bc9

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 899faf739088c467107ed0b2fbf370ec SHA-1: f7d3c6a5b2cf14c7d018c4e8ed64d24d1629f33c SHA-256: 2704310ba04a4bc97a519782afc926079e9e588a7ea0829436e00aa9c2d20c23

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros. The heuristic firing indicates the presence of these macros, which are often used to execute arbitrary commands or download malicious payloads. The macro content itself is heavily truncated and obfuscated, preventing a more detailed analysis of its specific actions or IOCs.

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` `9e57ece5d460f481b52e88d6bcebebcb18e5d28faf4b35fdb0851bcafc04c863`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	591622 bytes

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