Office (OOXML) / .XLSX malware analysis — malicious · 9cf3175e49f3e6d0

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: e5f703af1ca2600b331029a48242bf3f SHA-1: 6b2939af4c3125fe8bb39663de32ef5d22f6b75f SHA-256: 9cf3175e49f3e6d044f50e39352fe7c0a0193a69dc80fb35e874ff23868d781b

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an OOXML XLSX file identified as containing Excel 4.0 macros. The macro sheet appears to be attempting to execute a file path that resembles a document, specifically 'C:\ProgramData\excel.rtf', which is highly suspicious. This suggests the macro's intent is to download and execute a second-stage payload or to trick the user into opening a malicious document.

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` `90185b76e9d864c65158b3de837f088546b98c0e485dcb05211cb2cd6a3c8933`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	103158 bytes

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