Office (OOXML) / .XLSX malware analysis — malicious · a4cd8c804368eebf

MALICIOUS

Office (OOXML) / .XLSX

115.8 KB Created: 2021-03-29 19:55:06 UTC Authoring application: Microsoft Excel 16.0300

MD5: 7036a0ce1e351fef9357abb4b7967d0a SHA-1: 90be55c400c15df06b216b8f7452ea66044a868b SHA-256: a4cd8c804368eebf6c93bd4b306877fe6a562d2bee14dee5520c7488978defbf

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. While the macro content is truncated and obfuscated, the presence of such macros strongly suggests an attack pattern involving the execution of arbitrary commands. This is a common technique for initial access or downloading and executing further stages of a malicious payload. Due to the truncated nature of the script, the exact payload and delivery mechanism 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` `0d7587152bc0f528e5a96e63bf55d518f873054a6c56d73970556b76fed247db`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	94808 bytes

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