Qbot — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 ca641647b3e2102c…

MALICIOUS

Office (OLE) / .XLS

83.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 93383a84bdf0f5ff68b3bb6e30bcd2bb SHA-1: 455bb88e45935daa21c2bf86e2b48da0d7627025 SHA-256: ca641647b3e2102c7b8f0075f46d1e52618f9b597d4e5ca338dcfec8f1210c59
262 Risk Score

Malware Insights

Qbot · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious Link/Object: Malicious File

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro that utilizes dangerous functions, specifically the RUN function, to execute code. The macro reconstructs and calls three URLs, which are likely used to download and execute a second-stage payload. ClamAV detection further confirms this as a Qbot downloader variant.

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.
  • 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.
  • ClamAV: Xls.Downloader.Qbot1120210-9905989-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Qbot1120210-9905989-0
  • 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.
  • 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://ost.net.br/toXuNS00/l.html
    • https://atochagaleria.com.ar/CnijALAyxR/l.html
    • https://maberic.com/3XRJdBEjFc/l.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
f67984d5868d54299ad4a276a06ca6717af265485b5926455529fb317da6fd0a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11131 bytes

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