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

Static analysis result for SHA-256 e04d31201fecedc5…

MALICIOUS

Office (OLE) / .XLS

326.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 88f1b62de9b108ad46c070a0aca184d3 SHA-1: 4849bf96f7786123e7498dec11065308fc10443a SHA-256: e04d31201fecedc5f024d911bef10603b45bcaf80170eff25fd52f9d198fec66
340 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.004 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample contains Excel 4.0 macros and VBA code that leverage the URLDownloadToFile API. The VBA function 'Viurni' reconstructs the URL 'http://nuriatanes.com/ds/2112.gif' and uses it to download a file to the path specified by Sheets("Doc2").Range("AH7"). The presence of 'Auto_Open' in the XLM macros and the use of URLDownloadToFile strongly indicate a downloader functionality. ClamAV detection further supports this assessment.

Heuristics 7

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • 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.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • ClamAV: Doc.Downloader.Docusign0521-9864805-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
  • 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.
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
52ac84983ea537f13ec7e38300a206c002917bfa7200ec809f51e73b54e041b8		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1674 bytes
macros.bas
53d1a672c81b94e0436a54beda273f5769c7489beb41e537659c06874369a41c		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 2189 bytes

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