Office (OOXML) / .XLSX malware analysis — malicious · fe1b7296de9d25a7

MALICIOUS

Office (OOXML) / .XLSX

90.5 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: a92052a64d7bc3d0a3b9db6c27120998 SHA-1: 54ea2f8d44438e0d49c8b0bbef55197991322e42 SHA-256: fe1b7296de9d25a7cc1c1c8a98b488e2c65ca5c0431bef190297b621184e9634

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 an XLSX file. While the macro content is heavily obfuscated and truncated, the presence of a file path 'C:\ProgramData\a.exe' suggests the macro's intent is to download and execute a second-stage payload from a remote source. Further analysis of the obfuscated macro code is required for a more definitive understanding of its functionality.

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` `2aaf5f3c29e7709423469b71ce2554096fa6e7e4aa83d986a9e8d5ab92524e34`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7452 bytes

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