Office (OOXML) / .XLSX malware analysis — malicious · 4d08de581d78d51f

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: aed52a198baace5493dc864c4889ec7d SHA-1: 56cdb5ddde8b3e86f3a64c75c71735b418ed70e3 SHA-256: 4d08de581d78d51f8b0693fccdd6208212ce4639c3dc721d825190e11e0bd9ac

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.003 Windows Command Shell

The sample is an Excel 4.0 macro sheet, a format known for malicious use. The embedded macro executes a WMI command to launch 'mshta.exe' with a local file path 'C:\ProgramData\excel.rtf'. This strongly suggests the intent is to download and execute a second-stage payload, likely from a remote source, using the mshta utility. The specific file path and command are reconstructed from the macro's content.

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` `d62c074df6e8223543cd4355267d8e3c4b6dee2e5e0ed8002c48f8992ff9e021`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	67072 bytes

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