Office (OOXML) / .XLSX malware analysis — malicious · 394ec5e07720ee6e

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 54b76e5f1465538f75f338d22b2e6f88 SHA-1: 018faa460004340632063b86af8b668ade0d6443 SHA-256: 394ec5e07720ee6efbf8b39acc29d36728b33eebedc9c11498c09f1b4e2db01f

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. While the macro content is truncated, the heuristic itself strongly suggests that these macros are intended to execute arbitrary code, a common technique for downloading and executing further malicious stages. The absence of specific IOCs like URLs or hashes in the provided evidence limits further attribution.

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` `81cfd70d9749e24c11a43cf37e46fe389b80a5f8c744a45e326a1a28ba4d0a36`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	313896 bytes

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