Office (OOXML) / .XLSX malware analysis — malicious · 9526c196746d330e

MALICIOUS

Office (OOXML) / .XLSX

373.7 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: 6e7c1f6882a7519f9d187122533b265c SHA-1: 90df1559e5afd19b030be4507440045e31b38328 SHA-256: 9526c196746d330e8325d255833b0ccab912683d85ee577e96bb6aec34b8bac6

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. While the macro content is heavily truncated and obfuscated, the presence of such macros strongly suggests an attempt to execute arbitrary commands upon opening the document. This is a common technique for delivering secondary payloads.

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` `5bea04eb812011e374d9f73f5503c6ae5794c93fa6f16962cd3368e4b5043743`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	635650 bytes

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