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

Static analysis result for SHA-256 8f5a841c737e4c5d…

MALICIOUS

Office (OLE) / .XLS

31.0 KB Created: 2021-01-20 12:42:31 Authoring application: Microsoft Excel
MD5: d954ed8c20ab4924b5475a840f7d0c4f SHA-1: 30adc6091ed9b09839b2a396437cb172cd8f9777 SHA-256: 8f5a841c737e4c5d91f91f104773cb5f734ced65260c08957740352fba01d48d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a known technique for executing arbitrary commands upon opening the workbook. The heuristic firings indicate the presence of dangerous formula APIs, including the RUN function, suggesting the macro attempts to execute external commands. No specific family could be identified, but the technique is common for initial 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
d70f15216c84e7b0f670e19783554d14ed0bcf6fd9e247817a3347bf0a7d4c46		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3350 bytes

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