Office (OOXML) / .XLSX malware analysis — malicious · f15792ac4137b00a

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 561eb9d81e1b62607a65f319eee7de6a SHA-1: 45e33c1f9946ad9973a998cf67d26d4b8904694e SHA-256: f15792ac4137b00ab9647ec1114f2ea25d0ca8378af5231d75968288faa657f2

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. These macros are known to be used for executing arbitrary commands, serving as a common initial access vector for malware. The macro content itself was truncated, preventing a more detailed analysis of its specific actions or payload delivery mechanism. Therefore, the exact attack pattern and IOCs cannot be fully determined.

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` `6a295c48bbbba84238abda360d9050d1327227ac881ba4d3909314d6a910f302`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	386613 bytes

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