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

Static analysis result for SHA-256 5a41a88ded5487dd…

MALICIOUS

Office (OLE) / .XLS

331.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 837d8ad6c44e5e3ce57e5736b10af7dd SHA-1: 728147d50561efb20f922860a3f8ad90c88a014d SHA-256: 5a41a88ded5487ddd5e3d47771a77a6d4ff0b93aecb423bc95890645cacf4eb5
242 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros that are configured to auto-execute upon opening, indicated by the Auto_Open defined name and the use of dangerous functions like RUN and CALL. The macros attempt to construct and execute commands, including one that appears to be a call to ShellExecute via the CALL function, and another that constructs a URL string. The embedded URL https://ctxpress.com/ds/261120.gif is likely used to download a secondary payload. The ClamAV detection further supports its malicious nature.

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
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • 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://ctxpress.com/ds/261120.gif
    • https://ctxpress.com/ds/261120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
aa837a287543a9593dc9ad53c5a1043539349d9d7158b9d02f92e2bb7330dc0f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6677 bytes

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