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

Static analysis result for SHA-256 de59d6b484c2ffef…

MALICIOUS

Office (OLE) / .XLSX

106.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2022-05-31
MD5: d70705adb6a30898df9648003af46285 SHA-1: 93b3543b335cd7d428ea791d5173de41d7b84edb SHA-256: de59d6b484c2ffeff951ded086a67450efa84f91988aed8337585ab1281a897a
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The sample contains Excel 4.0 macros with an Auto_Open entry, indicating it will execute automatically upon opening. It also includes a lure to enable macros, impersonating a document signing service like DocuSign. The extracted URLs are likely used to download and execute a second-stage payload, as suggested by the presence of 'rundll32.exe' and 'DllRegisterServer' in the document body.

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
404f0e01d629b2f4d86e1affb27c10c9f07baccb002a01d7ecaf0166ee6b100f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3765 bytes

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