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

Static analysis result for SHA-256 d9be275feff4b338…

MALICIOUS

Office (OOXML) / .XLSX

457.6 KB Created: 2021-06-05 08:40:43 UTC Authoring application: Microsoft Excel 16.0300
MD5: 1ac719c744d22f42e4978e7b55828435 SHA-1: 4ddc7358f615987bf92ed9192430693db65b097c SHA-256: d9be275feff4b3383821b1483ba93424fb27aa40e138da41a91511193d9538cb
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications

The sample is an Excel file identified as malicious due to the presence of Excel 4.0 macros. These macros are often used as a delivery mechanism for further stages of an attack, such as downloading and executing additional payloads. The heuristics indicate that the macro sheet is stored under a disguised path, suggesting an attempt to evade detection.

Heuristics 2

  • 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.
  • Excel 4.0 macro sheet stored under disguised package path critical OOXML_XLM_DISGUISED_RELATIONSHIP
    OOXML package declares an xlMacrosheet relationship whose target is outside the canonical xl/macrosheets/ path. Excel follows the relationship type, while path-only scanners can miss the macro execution surface.