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

Static analysis result for SHA-256 55a9613f22af16aa…

MALICIOUS

Office (OLE) / .XLS

36.5 KB Created: 2020-11-27 10:37:44 Authoring application: Microsoft Excel
MD5: 3d3fe3e7981a26c0e66355de13e29c75 SHA-1: 80e2d01e4d039e05040a0085e26ff44dd4e6c5fc SHA-256: 55a9613f22af16aabc16459293e4ff7b13fd5686664caa6852d8a0feba5e0912
140 Risk Score

Malware Insights

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

The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Excel 4.0 Auto_Open macro. This macro is designed to execute automatically when the workbook is opened. The OLE_XLM_DANGEROUS_FN heuristic further confirms that this macro uses dangerous functions, specifically 'RUN', which is commonly used to launch arbitrary commands or download and execute further stages of malware. The presence of the Auto_Open entry is the primary IOC.

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
14edd4f40e3f1cabc4f5c88893329640341c1d121e11df2ce9ce0ae595a62f13
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6850 bytes