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

Static analysis result for SHA-256 0426cdbcc2cbd587…

MALICIOUS

Office (OLE) / .XLSX

192.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 3ced3a99f232fabf65e51f8a67ba68d2 SHA-1: 2e608a4fa4d17efb6763783424282011f3d328c0 SHA-256: 0426cdbcc2cbd587d32d4324bed89a4a80bca59bd880bdc8b1efc4810d4ed2bc
202 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a strong indicator of malicious intent. The macros are designed to execute dangerous functions, including downloading a file from the URL 'http://URLMonURLDownloadToFileArundll,DllRegisterServe' and potentially saving it as 'Frost.bitte'. The macro also attempts to contact 'gogorv.net/parseopml/intel.', suggesting it's a downloader for a second-stage payload.

Heuristics 5

  • 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.
  • URL reconstructed from XLM cell array (1 URL) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • 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 http://URLMonURLDownloadToFileArundll,DllRegisterServe
    • http://www.iec.ch
    • http://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#
    • http://ns.adobe.com/photoshop/1.0/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e28030e9d0d14a61d3f2dd5f3a502fe7843136dbc944ec7883cb7b380a59fbd9		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 12125 bytes

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