Office (OOXML) / .XLSX malware analysis — malicious · 366e871b1ad6123a

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 5c724af712a7a6d5c73bd868f3e4df2a SHA-1: afd50159b47465f2085cf1fa3ea39ea8b35ab214 SHA-256: 366e871b1ad6123aafc75fe8422388568ede34a8db2cf53329124a8a75fd1041

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The primary heuristic indicates the presence of Excel 4.0 macros. The extracted macro content shows a suspicious path "C:\ProgramData\Microsoft Excel.exe" which is likely an attempt to masquerade a malicious executable as a legitimate Excel process. This suggests the macro is designed to download and execute a secondary payload from a remote source, although the specific download mechanism is not fully visible due to truncation.

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` `44fd1c47b8478a40f16936787d02e2f713e0b88ba6e0e7cb9ec826b182dde961`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	106753 bytes

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