Office (OOXML) / .XLSX malware analysis — malicious · 595c56c71c91c470

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 751e07abc0bc08abf349a49fd8c81703 SHA-1: ad977311af2765089b9bffb5bb03cb26c6ab874c SHA-256: 595c56c71c91c470c05c6243e46835d1b25b15c247fcd2a025ef0369e6a6b798

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are known to be used for executing arbitrary commands, which is a common initial access or execution technique. The macro content itself is heavily obfuscated and truncated, preventing a more detailed analysis of its specific actions or payload delivery. Therefore, the exact family and IOCs cannot be confidently determined.

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` `f2e22df655bab4e1c49f3cfceca617e2e98d372e9a4d09116c692c10e302927a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7287 bytes

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