Office (OOXML) / .XLSX malware analysis — malicious · 46f0b4155e660ecb

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: b84fdd565a752aff149a76dacffc6743 SHA-1: 746960ed36d02aaa9312c309dbadb08c9077e7ae SHA-256: 46f0b4155e660ecbc16eacc26e44fa9f6c15a9a97d674d51ac7a7bf21b6bebbf

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The macro sheet contains obfuscated commands that ultimately reconstruct and execute the string 'wmic process call create 'C:\ProgramData\excel.rtf''. This indicates an attempt to download and execute a second-stage payload from a local file path, likely dropped by the macro itself.

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` `7c605f4e38343d2e82ddc21d83677d1cad35e1f38f553a973c40307677564ba7`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	57763 bytes

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