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

Static analysis result for SHA-256 b8eaa2375caaf314…

MALICIOUS

Office (OOXML) / .XLSX

1.13 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-04-26
MD5: 74a3b141ab1db5f033edfcce9612b1f3 SHA-1: 914a16666272a8fabcaf4d6757fdac6036216b76 SHA-256: b8eaa2375caaf3144d5752468b24de35815c25dfcd7cb61facb80937564fa7b2
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The critical heuristic 'OOXML_XLM_MACROSHEET' indicates the presence of Excel 4.0 macros. These macros appear to be designed to download and execute a secondary payload, as suggested by the embedded file names like '72696669.dat' and the potential path 'C:\Rujiky\Ubadada\Vertu.ooocxx'. The ClamAV detection further confirms its malicious nature as a downloader.

Heuristics 3

  • 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.
  • ClamAV: Xls.Downloader.GreenOffice12210-9918618-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.GreenOffice12210-9918618-0
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
24683ff192d5ff2bf2f841df675e1bec8a46ae42de534fcdbc64fb77dd4f33a5		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject2.bin 4465152 bytes
emf_00.emf
481999fdbcc1fde5a4e3a4e9970e4bbf3c8dbeb2e2a366cc840aa848993159f4		 ooxml-emf OOXML EMF part: xl/media/image2.emf 2159428 bytes
xlm_sheet_00.bin
6b81c949aeb8cc1680b035b1f27b241cd1f2f5d1dbdc301b1e32b5ea5bd4b23d		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 3304 bytes

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