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

Static analysis result for SHA-256 159259d8b9604c01…

MALICIOUS

Office (OLE) / .XLS

114.5 KB Created: 2020-05-28 22:58:23 Authoring application: Microsoft Excel
MD5: fb51102199d72c24c5aa73471fce4126 SHA-1: 40a01b1bb4a321801debd47460a97d16f26e4f54 SHA-256: 159259d8b9604c012a7eee07af2af3986a15c7bac87c16f5df288e983e6f0fe5
262 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled spreadsheet that contains an Auto_Open macro. This macro is designed to execute dangerous functions, including RUN, and reconstructs a URL from cell data. The reconstructed URL, 'https://yyauto.com.au/settings/boss.php', is likely used to download and execute a secondary payload, as indicated by the ClamAV detection signature 'Xls.Dropper.Agent-7946673-0'.

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 (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.
  • ClamAV: Xls.Dropper.Agent-7946673-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-7946673-0
  • 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://yyauto.com.au/settings/boss.php
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/photoshop/1.0/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
f367b09c9828a373cc0e1e0a3054e577ebf2235617060b481785ed7b71f847a6		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 68305 bytes

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