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

Static analysis result for SHA-256 fd55dc0884d9f29f…

MALICIOUS

Office (OOXML) / .XLSX

103.8 KB Created: 2021-03-29 19:54:15 UTC Authoring application: Microsoft Excel 16.0300
MD5: fb0001cba04e3a31ca9782a5c870e1d7 SHA-1: 62efe02310022219785d10ec370a8c4504d7c590 SHA-256: fd55dc0884d9f29f151f7e6226f7fb1be5d5b34f28fd0bc9610e291181a6f224
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros. The critical heuristic firing confirms the presence of these macros, which are often used to download and execute malicious payloads. The macro content is heavily truncated and obfuscated, preventing a more detailed analysis of its specific actions or IOCs.

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
d949a8b7ffa97589188bab8170d521758076d1b4c068e080055a6adbc7dea520		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 98782 bytes

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