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

Static analysis result for SHA-256 778d8e01632649b1…

MALICIOUS

Office (OLE) / .XLSX

329.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 8923aefc97b04ca0fbeece457d281967 SHA-1: 554289f8cb4a13cf1f38660a78c4292aafe6d37c SHA-256: 778d8e01632649b18af370f0e30609975c05d3219f9e8c7c511fb54dacb4ccd2
242 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros with an Auto_Open entry, which is a critical finding indicating automatic execution upon opening. The macros utilize dangerous formula APIs, including RUN and ShellExecute, to initiate an external process. This strongly suggests the file is designed to download and execute a secondary payload from the embedded URL, https://nomzoo.ml/ds/161120.gif.

Heuristics 6

  • 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.
  • ClamAV: Doc.Downloader.Docusign0521-9864805-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://nomzoo.ml/ds/161120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
b74fbb14c9dd0283fe5b35630158622cf58bbddcd03d161d30bf64d1f40271a4		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7889 bytes

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