Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 66d30fcba7de6b11…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:29:11 Authoring application: Microsoft Excel
MD5: 1121ab3027e0ef887ffc8fe1834bb972 SHA-1: a0433631203be549ed9820b9fb4c7baf692cb170 SHA-256: 66d30fcba7de6b119a4ab6a2c058a3b12cbdfdbcdbefd712ba8c2a745ebfc0b5
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating automatic execution upon opening. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands. This points to a macro-based downloader attack pattern.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
cdcdf47e270dab29359b1bb1b064e77cad2b7a5a204010927e17a4c8a4a6adc1		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6695 bytes

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