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

Static analysis result for SHA-256 85c98778c60684dc…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:27:40 Authoring application: Microsoft Excel
MD5: 042cec9835b3d407ae813a0367469113 SHA-1: 64199ca3c509855978720b735893d58a87968456 SHA-256: 85c98778c60684dca4d872958338ed89276c6d95bbc7225c9eafcfc2ef679d83
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains critical Excel 4.0 macro heuristics, specifically an Auto_Open defined name and the use of dangerous formula APIs like RUN. The presence of an Auto_Open function indicates that the macro will execute automatically when the workbook is opened. The RUN function is known to be used for executing arbitrary commands, suggesting this file is designed to download and execute a second-stage payload. No specific family could be identified, but the technique is common for initial access.

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
2be0bfdd4010fec3b7e21880e18cae7baaf11849311f1b462f9f8238c99fabea
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6472 bytes