Office (OOXML) / .XLSX malware analysis — malicious · 66855182d76be9e5

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 22b2cd9d5961d5a4ea0c866f5e9b58e6 SHA-1: 0e821f0310c2feee353ae42ad91795e005e54e83 SHA-256: 66855182d76be9e5dca7e2dcdda65385eeb5624b967ad4f9fc9321b2b35d9996

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are capable of executing arbitrary commands, which is a common technique for downloading and executing further malicious payloads. The specific commands are obfuscated within the macro sheet, preventing a more detailed analysis of the exact payload or destination.

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` `d2e0b2b109af8b360fae6b9d0975c335ca6585b2ae64db41783489d7951dcd0f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4691 bytes

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