Office (OOXML) / .XLSX malware analysis — malicious · 4989949bd322678b

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: afc37fe99822a78b3c2b87e30c559b00 SHA-1: 26bf8bdf3101de21c750f734c16842c8f1c48a2c SHA-256: 4989949bd322678be1f9f12b399a7714d9c4df1b0b4c4374c04ed671dc507d7d

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. While the macro content is heavily truncated and obfuscated, the presence of these macros strongly suggests an intent to execute arbitrary commands. This is a common technique for initial access or downloading and executing further stages of malware.

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` `de64e3419b82a4bae912a931513215b4a820e739903060dbd94814b961946dbe`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	232486 bytes

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