Office (OOXML) / .XLSX malware analysis — malicious · 375197f97fb0cd7b

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: cacd97b4f9f420d092e85b2945985b82 SHA-1: 14d2bc91b4f5becaefab51351d584419570f61bb SHA-256: 375197f97fb0cd7b54ecd202cb46f7051cb7b825970b30a71dbc5b9dafc7b56c

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel 4.0 macro sheet, a known technique for executing malicious code. The macro appears to be attempting to execute a file named 'excel.rtf' from the 'C:\ProgramData\' directory. This suggests the macro's purpose is to download and execute a second-stage payload. Due to the obfuscated nature of the macro content, the exact download mechanism and payload are not fully discernible, leading to a moderate confidence score.

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` `7e49593d31ead91a223002a9b38bd4a0a06dc45cd1fdc01842d219f5a1352a58`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	280056 bytes

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