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

Static analysis result for SHA-256 c095da601306b7b3…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:41:12 Authoring application: Microsoft Excel
MD5: f3b7b67652ddb27a3cf44684c8116ae5 SHA-1: f70a04b37a7ca48a07d9ce5b2fbafd6bbeafb6b7 SHA-256: c095da601306b7b302462f36d3b945e6f85b64a7d46ac5f944802040eb5b62a9
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious Link

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open function. This function is known to be used for executing arbitrary commands, as indicated by the 'RUN=0' heuristic firing. The presence of an Auto_Open macro in an XLM sheet is a critical finding, suggesting the file is designed to run malicious code upon opening.

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
6ca6d2d21c948a474a7c1faa617f15cdd5f080367e3f47f4e07dbd9714703bd8		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6531 bytes

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