Office (OOXML) / .XLSX malware analysis — malicious · 8e5c82972394cff6

MALICIOUS

Office (OOXML) / .XLSX

67.4 KB Created: 2021-03-15 18:27:04 UTC Authoring application: Microsoft Excel 16.0300

MD5: a101a6bc935a375b1eb062c844390067 SHA-1: 0d9d6d5366d0f00e5e0ae249acd19140cf132975 SHA-256: 8e5c82972394cff6ed36dcb0d8becaed4414716f3e34827069370e01043bc86d

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The macrosheet content is heavily truncated and obfuscated, preventing a detailed analysis of its specific actions. However, the presence of Excel 4.0 macros strongly suggests an attempt to download and execute a secondary payload, a common technique for initial access.

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` `9e70285271278fc26a2c0e73caa0e35a387a767eaa1109ebe79ba895c416c949`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	92701 bytes

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