Office (OOXML) / .XLSX malware analysis — malicious · 19c881718148dff8

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 6d933d8cc31c87fff03225a1cf4dc7cf SHA-1: c7fd2a3b17d69f4fef4a9dfd3fd79e914e4c81ed SHA-256: 19c881718148dff81821ae1c4f18536fe7c07196b2d581ad0b09fcf26f5cfc8f

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059 Command and Scripting Interpreter

The primary finding is the presence of an Excel 4.0 macro sheet, indicated by the OOXML_XLM_MACROSHEET heuristic. This type of macro is capable of executing arbitrary commands. The macro appears to be attempting to execute a file located at 'C:\ProgramData\excel.rtf', suggesting a downloader or initial execution stage for a malicious payload. The exact commands and their purpose are obscured by the macro's structure and truncation, leading to a moderate confidence level.

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` `edc03787075ed36c8e604b59b11c4e0f820c86f9a3d077b340789d6fba6c479d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	122494 bytes

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