Office (OOXML) / .XLSX malware analysis — malicious · 2646e0b7f4010fc3

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: e1a517cccb0156d9effac26d7a063524 SHA-1: 81043b6907ee9579d4388fdb9bf9feca65b40f11 SHA-256: 2646e0b7f4010fc3f87c6f6823a50b8b3f3177e1c18510cac83768c8a3783ac2

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 additional payloads. No specific IOCs were extracted, and the macro content was truncated, limiting further analysis.

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` `13790fe5d99bf92fd2eca138874f6d81b91237fd286d11f4214ccda91dcf8615`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	641509 bytes

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