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

Static analysis result for SHA-256 75b52b94778899c3…

MALICIOUS

Office (OLE) / .XLS

44.5 KB Created: 2020-11-05 11:46:09 Authoring application: Microsoft Excel
MD5: 6666ddc3e1e44258414a0825cb33960a SHA-1: ebc5ffea3d0ecc2a7031f04403df316947b8cbd3 SHA-256: 75b52b94778899c3d6fd0d3357fc04a604d765a89dcf045707df63023bf6b9a2
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 defined name, which is a known method for executing arbitrary commands. The macro sheet contains a reference to 'Auto_Open', suggesting it will run automatically when the workbook is opened. This functionality is leveraged for client execution.

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
f91783fcf45dc8652b547f68b72433c1ea2818d4396f59e075969ebda3015c98		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 12457 bytes

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