Office (OOXML) / .XLSX malware analysis — malicious · 75ff9ff14b88646c

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 607ed63abda24d4af47aafa487b085d9 SHA-1: af00a4b4ad83b8473abda03c815531fca19aac38 SHA-256: 75ff9ff14b88646c851bb3e7b1aaf362d5dd458b4eae2b4f8c31cf317e09d755

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. These macros are designed to execute arbitrary commands, a common technique for downloading and executing further malicious content. The specific commands within the truncated macro sheet are not fully discernible, but the presence of XLM macros strongly suggests a downloader or initial execution stage.

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` `411dc4435a1465e7062b84144a870cd04414dd403b56411692a69ab0ffcbd3d1`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	359343 bytes

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