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

Static analysis result for SHA-256 b58260404103da94…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:46:44 Authoring application: Microsoft Excel
MD5: 3abb49acaa1ddf2b04ecb114520f5c95 SHA-1: 8584e40cef337827ac3c1665ec59e365d041e87a SHA-256: b58260404103da9452e93f2230f70594bc4805244b438ad81ee06a207a0e7250
140 Risk Score

Malware Insights

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

The file contains critical heuristic firings indicating the presence of Excel 4.0 macros with an Auto_Open defined name. The macros utilize dangerous formula APIs, specifically the RUN function, which allows for the execution of arbitrary commands. This suggests the file is designed to download and execute a second-stage payload or perform other malicious actions 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
633f88d9f5ec338237e29d50d16dac23194c41c3ab2fb538c975fbd48e4219ba		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6653 bytes

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