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

Static analysis result for SHA-256 d9b4a86965789c70…

MALICIOUS

Office (OOXML) / .XLSX

97.4 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-11-07
MD5: 5ced096e35075e9a2b32c7128e048691 SHA-1: a137ba97c79695c3525af6ac5644045c136e0cdb SHA-256: d9b4a86965789c70ae466ad22d5d16f32920d7318fccd1d53f57fa3513504a34
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet. The macro sheet contains strings that appear to construct a path to a file named 'Excel.rtf' within the ProgramData directory. This suggests the macro's purpose is to execute commands, potentially to download and run a malicious payload from that location.

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
0affa7b7e456a5ce8509ca666589cd985a725a44f7d9c6acc5ed6a4f3083e2a7		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 108597 bytes

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