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

Static analysis result for SHA-256 1c18f8b1c63d3a2b…

MALICIOUS

Office (OLE) / .XLS

285.5 KB Created: 2020-06-18 09:21:42 Authoring application: Microsoft Excel
MD5: a50def1e275b0396665f203ea1c6a779 SHA-1: 9ac46e4823f625c61c0ce53a497263e806f9c80f SHA-256: 1c18f8b1c63d3a2ba5702aee7047bc161ab5057fbd3470dded69a50abb9032a3
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

This Excel file contains Excel 4.0 (XLM) macros, specifically an Auto_Open function. The presence of a dangerous formula API (RUN=0) indicates that the macro is designed to execute arbitrary commands. The document body contains random-looking strings, suggesting it is a lure for a malicious macro execution. The XLM macros are the primary mechanism for executing the malicious payload.

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
937c465dcd62131637bc80b17e8528bf40a1f799da0d3096be7a4a35bd173799		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 57507 bytes

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