Office (OOXML) / .XLSX malware analysis — malicious · cf819b1bc16ec7bc

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: eb3eb1d458d0dafa554eba427cdda2f1 SHA-1: a1232e31f04ab669c00c8c1f6b067e08b12c6a0c SHA-256: cf819b1bc16ec7bc4a669cd5942731f5525c2338c61d46824dac403014c4755f

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are capable of executing arbitrary commands, which is a common technique for initial access or payload delivery. The macro content was truncated, 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.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `6cd9407a9414c295310528c1799169b4a4fa807d9792ed559fcc97713b2df2ea`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	414348 bytes

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