Office (OOXML) / .XLSX malware analysis — malicious · f0b8013ca450beb4

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 7759e7aecabc6af955604daee9eb2d8a SHA-1: 7e1c0fbdfadec2f0508ea52cf6f7836420b25d7e SHA-256: f0b8013ca450beb465c4951395e436e2ac6cad50be44f01a92378f611d289a7e

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel document containing a macro sheet, as indicated by the OOXML_XLM_MACROSHEET heuristic. The extracted macro sheet (xlm_sheet_00.bin) is likely responsible for downloading and executing a secondary payload. The exact functionality is difficult to determine due to truncation and obfuscation, but the presence of Excel 4.0 macros strongly suggests a malicious intent to compromise the user's system.

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` `ee7a4f3feb9df1c9706d66acf9e0acef8ab0d03c6ab2f2ba4672226d294bbf11`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4264 bytes

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