Office (OOXML) / .XLSX malware analysis — malicious · 8ef94dc41994e020

MALICIOUS

Office (OOXML) / .XLSX

65.3 KB Created: 2021-03-14 19:50:37 UTC Authoring application: Microsoft Excel 16.0300

MD5: b938a5ab9ba20326ec988d90d8cd2da4 SHA-1: 57fe9b3c288159e576b4d692ab98d593ee5bbcb7 SHA-256: 8ef94dc41994e0205ab9e85ab8654f2d1c97f0f8d0c3e8a5446cdd6893777c5a

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros. The macros are heavily obfuscated and truncated, making it impossible to determine their exact function or reconstruct any specific IOCs. However, the presence of XLM macros indicates a malicious intent, likely to execute arbitrary commands or download further payloads.

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` `b2408d0b6c593d5edd3aaf5ea23f0796ace10bfc1a0a7658009a14a543f61ffe`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	97004 bytes

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