Office (OOXML) / .XLSX malware analysis — malicious · fbeed1cab42141af

MALICIOUS

Office (OOXML) / .XLSX

64.4 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 1d4bb694f87482936848834866c694af SHA-1: 58674928725c45e73825f44df619f18a07c5aa1c SHA-256: fbeed1cab42141af77f6d5991f16f6bd7f8b7b5f73eeb3e8f02540b461bfaa93

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel document containing Excel 4.0 macros. The macro executes a 'wmic process call create' command to launch a file named 'excel.rtf' from the 'C:\ProgramData\' directory. This suggests the macro is intended to download and execute a second-stage payload. The exact nature of the 'excel.rtf' payload is not determinable from the provided evidence.

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` `9bf39e4ae27925199a79ac762e04ef620877a9ca35b97c152c4637c9c61dd2ef`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	106486 bytes

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