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

Static analysis result for SHA-256 f66b8ee9bea7ec40…

MALICIOUS

Office (OLE) / .XLS

31.5 KB Created: 2021-01-20 13:30:18 Authoring application: Microsoft Excel
MD5: 8d032792c133999688928c90de24ae19 SHA-1: e5fdf654d2dbcd1936327a49fce654b66e6fbc86 SHA-256: f66b8ee9bea7ec406c6a88ccfb54c447afc3e4c44ae08c071b97beb74b66e2eb
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1059.001 PowerShell: PowerShell

The file is an Excel 4.0 macro-enabled workbook. Heuristics indicate the presence of an Auto_Open macro and the use of dangerous functions, specifically the 'RUN' function. This suggests the macro is designed to execute arbitrary commands upon opening the workbook, likely to download and run a second-stage payload. The specific commands executed by the 'RUN' function could not be fully reconstructed due to incomplete parsing of the macro sheet.

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
f6de68acf365fd8d479022143accbf35f2872fd2926a07603f72b871d71fa148		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3523 bytes

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