Office (OOXML) / .XLSX malware analysis — malicious · 8ab1709f682e801b

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 0830eb539848095b5e55d133a66be63a SHA-1: ecaeae44e7b3dda48a5839a4f0ea140f0e83067b SHA-256: 8ab1709f682e801b8f8176d7918fb53d071c06ac24a1b9d988542b201bdb0100

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros. The extracted script content reveals a hardcoded path, 'C:\ProgramData\fnsfunSfgRgnKjfsGnd', which is likely used to stage or execute a downloaded payload. This suggests a downloader or droppper functionality. The family is unknown due to the obfuscated nature of the macro content.

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` `c0305d0c93b4a75bd3245453620b4fdb5e91e2a97e877432ebecc40a221624e7`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4440 bytes

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