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

Static analysis result for SHA-256 dca1061b4c3303f5…

MALICIOUS

Office (OLE) / .XLSX

195.5 KB Created: 2021-10-27 10:31:49 Authoring application: Microsoft Excel
MD5: be6910686587fe6e152b7f6aa1643e64 SHA-1: 92da4733157b0b794c03a3338ff1a7436b7a48f5 SHA-256: dca1061b4c3303f5d09fa47ecb70cec7532ecf1f6205c622a34386f5e2d0a1ee
82 Risk Score

Malware Insights

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

The sample contains Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN heuristic. The macro attempts to construct a path to 'C:\ProgramData\XxbjvUKPAQZ.vbs' and uses FOPEN to open it, suggesting it's designed to download and execute a secondary payload. The embedded URLs, although currently flagged as benign, are likely the source of this payload. The ALERT function is used to display a fake error message to the user.

Heuristics 3

  • URL reconstructed from XLM cell array (3 URLs) 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 https://cdn.discordapp.com/attachments/911255825308348439/917344555379085402/efrXXwhatsupmotherfuckers.bin
    • https://cdn.discordapp.com/attachments/911255825308348439/917344562354221086/bfugrKhVwhatsupmotherfuckers.bin
    • https://cdn.discordapp.com/attachments/911255825308348439/917344568125562890/GuJPZwmNijUwhatsupmotherfuckers.bin

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
7ad1e562510679b79dbb5b875a544c6a2efbebc385edba17e9e5ba9be4ebf7d3		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2410 bytes

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