Office (OOXML) / .XLSX malware analysis — malicious · ecf8281513839042

MALICIOUS

Office (OOXML) / .XLSX

344.9 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: 8557db5993d920a52b6cbeae58336a2f SHA-1: afc545a12b555ec05a0d04bc3e9d96e1fc6d9e8f SHA-256: ecf828151383904275fac7e728e769adcf46a23738f2f33b6d1e98e19c5b3e30

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, which is a known technique for delivering malicious payloads. The macros themselves are heavily truncated and obfuscated, preventing a detailed analysis of their specific actions. However, the presence of these macros strongly suggests an intent to execute arbitrary code.

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` `9e02365a1264d6e5d4bc93065115f0fb0e964087d091bfe0ea97c39a8077ee49`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	285706 bytes

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