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

Static analysis result for SHA-256 999c5f5c362b730f…

MALICIOUS

Office (OOXML) / .XLSX

342.4 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: b022b36862b56d9da2303ffcbb4a67ab SHA-1: e3af13c011041ca7acbe9c72f1307cf83d8fdc1e SHA-256: 999c5f5c362b730f9abaf43fe6f8a8e162c0f98ff9523f2e3fc22698ab5acb09
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The macrosheet content is heavily truncated and obfuscated, preventing a detailed analysis of its specific actions. However, the presence of Excel 4.0 macros strongly suggests an attempt to execute arbitrary code upon opening.

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
604a3f11b9052ce6a48c300fc2643a4a570c391eaaab3b1cc04408f5e4f361bc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 646845 bytes

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