Office (OOXML) / .XLSX malware analysis — malicious · d67a63ae0ccd792f

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 032012fb109426e9e03b0e039e558903 SHA-1: 18557fc96d9e26dc2d9fa1b708460a5f2eaab4fc SHA-256: d67a63ae0ccd792f11314f0c31d5a2c70fd8ef165b9ab326863149a9f32d960c

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The file is an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The macro sheet contains obfuscated commands that, when deobfuscated, reveal a call to 'wmic process call create' to execute a file named 'excel.rtf' located in 'C:\ProgramData\'. This indicates the macro is designed to download and execute a second-stage payload. The family is unknown as no specific indicators point to a known malware family.

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` `c70b4c7d9353d56a3bd2b7cd6162cfab61b2348fdc88d83ee0010c621c9a30aa`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	160081 bytes

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