Office (OOXML) / .XLSX malware analysis — malicious · a280bd9dda5d7761

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: e8475224481d49893878534d82b3cfce SHA-1: fbb7b87b742f82d59f7eb4591fac41301f097b31 SHA-256: a280bd9dda5d7761bd7a7a64f72d80816e5258c2acc3c55fd2ad37f373483ff9

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros. The macros appear to be obfuscated but contain references to a file path 'C:\ProgramData\a.exe', suggesting an intent to download and execute a payload. The specific functionality of the payload cannot be determined from the provided data, leading to an unknown family classification.

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` `36895ded3b3fa5ab2a181ef44c322e518a30e6d120ffb630f45355d98c84b115`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7509 bytes

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