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

Static analysis result for SHA-256 238486ff22b01664…

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2020-11-25 12:49:49 Authoring application: Microsoft Excel
MD5: 94a8db7ddbd42b6414e9d4de3be20afb SHA-1: 592ceacc3ec491605dae59d135233023e9c1b4f6 SHA-256: 238486ff22b0166493462b67548198ed2cd2f447c7dd053b620cab9d3c576f6f
140 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro and the use of dangerous functions, specifically the RUN function, which is commonly used to execute arbitrary code. The macro sheet itself contains a large amount of obfuscated data, suggesting it is designed to hide malicious commands. No specific URLs or hashes were extracted, but the technique strongly suggests a downloader or initial execution stage.

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
93434a2da4a93afebfe8f9ec1a7b923e60cf7c4807741b006cb8216cd43e5baa
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6459 bytes