Office (OOXML) / .XLSX malware analysis — malicious · e564b47be16aaa8e

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 962f3671849d38db87cccb8c366f4387 SHA-1: 751e04d23f7c3ed67e8436838d7e52fa134a82ca SHA-256: e564b47be16aaa8ebccc4b8169b75673558296a970b0c2c252f4323702fd1b7f

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are capable of executing arbitrary commands, which is a common technique for initial access or payload delivery. The macro content itself is heavily truncated and obfuscated, preventing a more detailed analysis of its specific actions or the reconstruction of any URLs or commands.

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` `3f96f397c34c0663197231e8d5c5226952a1296855b65fc4a752a4409deac712`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	612856 bytes

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