Office (OOXML) / .XLSX malware analysis — malicious · 13e88e61d65d9735

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 63280274ac03ffa8967fc5bb0e6bd4d5 SHA-1: a69ff974fbeb8caf2b8fb2dee1e819913abee8ad SHA-256: 13e88e61d65d9735f64ef3b513a55bd50fb4551dc162bb5506c77f4abc6c464e

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file was identified as an Excel 4.0 macro sheet, which is a known method for executing arbitrary commands. The macro sheet content is heavily obfuscated and truncated, preventing a detailed analysis of its specific actions. However, the presence of XLM macros strongly suggests an intent to execute code.

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` `d9e8154175dc6df9a403b7d48d709da8cb2f2f89473160757623bf0c32a705fd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4280 bytes

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