Office (OOXML) / .XLSX malware analysis — malicious · e1e6aac22c713096

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 72238cde759757aea0353a5eeaa3bfdf SHA-1: d4474ede904e44bbf9b7ca7ca8c3679b0287c690 SHA-256: e1e6aac22c713096ba829eb47194059b4dd7cca08dfc4422b44c2f04bdf00e3f

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros. The extracted macro content reveals a command that uses `wmic` to execute `mshta` and create a file named 'excel.rtf' in the ProgramData directory. This suggests the macro is designed to download and execute a second-stage payload, likely for further malicious activity.

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` `8fd90e1bf1713688666b4b92f41922b0bd17ec2743e96528188dbe877673d464`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	115190 bytes

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