Office (OOXML) / .XLSX malware analysis — malicious · b7e7a71b28c025c4

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 81ba2eb2f45b19970f564129fbb9f0e4 SHA-1: 42b53db95d3883301b4d5564fc0497d2da0d9f23 SHA-256: b7e7a71b28c025c4150c48b44add09b24c959f3675a02ab852c6fe38e5045a93

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. Excel 4.0 macros are capable of executing arbitrary commands, which is a common technique for initial execution of malicious payloads. 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` `f8cb96927ec75914cf3d121877511fe22065a9974ac1440e268c1d682f7ebb02`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	250434 bytes

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