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

Static analysis result for SHA-256 34258b85dd133fe8…

MALICIOUS

Office (OLE) / .XLS

36.5 KB Created: 2020-11-25 13:53:47 Authoring application: Microsoft Excel
MD5: 44f970b568ccc2f2d2cdc6e76cf92ea0 SHA-1: 26a8660048e2edca347fc2c8305651fca95b9b53 SHA-256: 34258b85dd133fe87643ab9d2653f91894a343c4e45b0abfb4fdc34d6b61a009
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating potential for arbitrary code execution. The presence of dangerous formula APIs like RUN further supports this. The macro sheet likely contains obfuscated code designed to download and execute a secondary payload, a common technique for initial access and further compromise.

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
f90c6f2786ff4b9c356d9ed4d086b78d9a4b39ae7db17f1f18532520d1f24c8e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6473 bytes

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