Office (OLE) / .XLSX malware analysis — malicious · 87d70d89dc333324

MALICIOUS

Office (OLE) / .XLSX

274.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2022-09-22

MD5: 385b9251ee073b2460a3b3d1981d107d SHA-1: c929d2386c06aa6eecbe1f4aa360c6a624dd3d92 SHA-256: 87d70d89dc33332415390de7a4e9d28113192637a3a4fc647757e3bacdbe17df

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

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 embedded text suggests an attempt to download a DLL from 'parkisolutions.com/nerugin.dll' and execute it using 'rundll32.exe'.

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.

Filename	Kind	Source	Size
`xlm_macros.txt` `84db8022cd9373e19b3b88e0e3e8c161c0d41468768a7f50d479104c806845c5`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3274 bytes

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