Office (OOXML) / .XLSX malware analysis — malicious · a12bcb52bc373958

MALICIOUS

Office (OOXML) / .XLSX

76.7 KB Created: 2021-03-14 19:50:37 UTC Authoring application: Microsoft Excel 16.0300

MD5: 4f9da79a659fcfc70db7a86c87fede84 SHA-1: 4d731ec8a09cbf09058dab36b5b615dd56d12951 SHA-256: a12bcb52bc37395897705cf344cb7d63f3e0007c2a8788650c7f7dd8464514d9

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 truncated, the presence of such macros is a strong indicator of malicious intent, typically used to download and execute further stages of an attack. The file is identified as malicious with a risk score of 60.

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` `b2408d0b6c593d5edd3aaf5ea23f0796ace10bfc1a0a7658009a14a543f61ffe`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	97004 bytes

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