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

Static analysis result for SHA-256 5d4322fe4835f245…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:38:30 Authoring application: Microsoft Excel
MD5: ea8ebb37387cb372eeb901e4dafb4c5f SHA-1: 28a0c6de100112b986ffe5d7af2fba370f616476 SHA-256: 5d4322fe4835f245d2208154dc4f2bb05255cdb5596cb9e6831fd64c70455a19
140 Risk Score

Malware Insights

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

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a known method for executing malicious code. The macro sheet contains a dangerous formula API call, specifically 'RUN', suggesting it's designed to execute arbitrary commands. The document body contains obfuscated text, likely part of the macro's payload or lure.

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
3433b581cc6499f67536ace1fe78d9181371eb6c66cdbacc13c6baaaac9bdb5c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6686 bytes

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