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

Static analysis result for SHA-256 b736b5bd88d1da16…

MALICIOUS

Office (OLE) / .XLS

110.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 1bef9e815b731aa2abb875e7407f7d0f SHA-1: 3c76b8bc108028aca363b7f5dc6a6f26ddf24a1b SHA-256: b736b5bd88d1da16aa703561677ae1ab16cd264e7e0ee84a858ac1332c9fa0c5
240 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1218.010 System Binary Proxy Execution: Rundll32

The file contains Excel 4.0 macros, specifically an Auto_Open macro that utilizes dangerous function APIs like RUN. The macro is designed to execute a command involving 'rundll32 DllRegisterServer' and a URL pointing to a GIF file, which likely serves as a downloader for a malicious DLL. The presence of these elements strongly suggests a downloader attack pattern.

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
  • Visible LOLBin command execution instruction high SE_LOLBIN_RUN_COMMAND
    Document contains instructions or visible command text involving Windows script/execution tools such as PowerShell, mshta, cmd, rundll32, or regsvr32
  • 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://bucklindata.net/ds/061220.gif�
    • https://bucklindata.net/ds/061220.gif
    • http://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • 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
700d528fd593784369da26777fb00cef6c34efb4cbfae84251e80320e3e8a815		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1943 bytes

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