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

Static analysis result for SHA-256 22bbe386343a8bb1…

MALICIOUS

Office (OLE) / .XLSX

274.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2022-09-22
MD5: b80dd643e5b31f9724c549a77fe06a79 SHA-1: a46f68a3aba17153e57d01970cb41f4cdb64a05a SHA-256: 22bbe386343a8bb1681d9bbb7d283a573344bad44b7eec6001ccbf96078c1a56
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros with an Auto_Open entry, indicating automatic execution upon opening. It also includes a lure to enable macros, impersonating a document signing service. The macro appears to download a DLL from 'https://parkisolutions.com/nerugin.dll', which is then likely executed.

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
  • Document signing service impersonation lure medium SE_DOCUSIGN_LURE
    Document impersonates DocuSign, Adobe Sign, or a similar signing service in a signing-request context

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
84db8022cd9373e19b3b88e0e3e8c161c0d41468768a7f50d479104c806845c5		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3274 bytes

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