Office (OLE) / .XLSX malware analysis — malicious · 5aaa894a40f3b1ef

MALICIOUS

Office (OLE) / .XLSX

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

MD5: ed442e947992e0d4adc4be14d70c530c SHA-1: d3391f571b8da0ee4499fae22b4b40ce96f707d3 SHA-256: 5aaa894a40f3b1ef930944492103b9ace2fb5861ac89d1f3861afdbad14fa1be

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 defined name, indicating automatic execution upon opening. It also includes a lure to enable macros, impersonating a document signing service. The embedded text contains a URL that likely points to a secondary payload, 'https://parkisolutions.com/nerugin.dll', which is then likely executed 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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