Office (OOXML) / .XLSX malware analysis — malicious · d8a728cb3a50a7ad

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: eb0274754ee4f3e1c479f54055a0bfcd SHA-1: 2a4434871a3e64f6d34c952ac2058669a71e6e5c SHA-256: d8a728cb3a50a7ad7025ba0229f1b0d185492c37e122437c62890e51b768c56b

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing an Excel 4.0 macro sheet. The macro appears to be designed to execute a command, specifically referencing a path 'C:\ProgramData\fnsfunSfgRgnKjfsGnd'. This suggests the macro's purpose is to download and execute a second-stage payload from that location or a related one. The macro content is heavily obfuscated and truncated, making a precise determination of its full functionality difficult.

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` `c4422fc7c432bd5a7a10e538a8661bc5fb8803f6feebd9532ae6a39ab9dcedb7`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4160 bytes

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