Office (OOXML) / .XLSX malware analysis — malicious · de1aa5d949fc790d

MALICIOUS

Office (OOXML) / .XLSX

113.9 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 64173485e31d70226f5285e73e59eb5d SHA-1: a40d26c0df69b103bd1e30cffa8b75ab2b94bf2a SHA-256: de1aa5d949fc790d34ea87d21e364c06fdcb81565f413d4befa8d3c4a86c6d1c

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are known to be used for executing arbitrary commands, making this a likely initial stage for delivering further malicious payloads. No specific family could be identified, and no IOCs were directly extractable from the truncated macro data.

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.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `8361f3feb09d091ab90ef68cb749d8cedbcd406de619be18c6da4d1fa3430ed2`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4689 bytes

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