Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 f8177ba2eeeb3ba3…

MALICIOUS

Office (OOXML) / .XLSX

70.6 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 138263b7c164504e5896f4ba28576114 SHA-1: c208cb10f3bd81b5f556d46bdb9a511f6a4ec651 SHA-256: f8177ba2eeeb3ba3f6e3cb62d55ad1b80fbd5910bcfe43cad3c3d11a5c873719
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution

The file is an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The embedded macro executes a WMIC command to create and launch a file named 'excel.rtf' from the 'C:\ProgramData\' directory. This indicates a likely attempt to download and execute a second-stage payload. The exact nature of the RTF payload is not determinable from the provided evidence.

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.

FilenameKindSourceSize
xlm_sheet_00.bin
a71abce908662bd59408fcf6b5e93abfce2a33d216865e6b8f1f31abd96b46f5		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 157098 bytes

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