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

Static analysis result for SHA-256 0c4bd354fb87a677…

MALICIOUS

Office (OOXML) / .XLSX

60.4 KB Created: 2021-03-14 20:07:08 UTC Authoring application: Microsoft Excel 16.0300
MD5: 82f6cf22800ef846039efb29938c1e4e SHA-1: f8172674c0c761b67350d9811735e3762c957e72 SHA-256: 0c4bd354fb87a6770d649f382821dc4b62eb0c91cce45d9646cf9c535161d22c
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. These macros are likely designed to download and execute a secondary payload, a common technique for initial compromise. The specific macro sheet artifact is identified as a potential IOC.

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
f42b99f980048828f35f257c1a9803b6fb8cffad4abcb712ecf7dc8a682ba589		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 92580 bytes

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