Office (OOXML) / .XLSX malware analysis — malicious · 3aba474b330e34be

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 84db8e976c2b36c0cd8dcc4a2e21f759 SHA-1: 4821e78a4aa28a8fc45cc73fe2f48677d3a238ce SHA-256: 3aba474b330e34be2bb82bda6d36b44948069051af351928edefca5dbd803d20

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Visual Basic

The critical heuristic 'OOXML_XLM_MACROSHEET' indicates the presence of Excel 4.0 macros. The extracted script content reveals a 'wmic process call create' command that attempts to execute 'mshta C:\ProgramData\excel.rtf'. This suggests the macro's purpose is to download and execute a second-stage payload from the specified path, likely leading to further malicious activity.

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` `dd0a5080953f457f87d3c167709ff4f42385f9c4b46d9e3e3dfd111b47742f7b`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	168109 bytes

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