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

Static analysis result for SHA-256 1553df040aa4a4ca…

MALICIOUS

Office (OLE) / .XLS

331.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: db20a5b5deff4c08569e75a07735a15f SHA-1: ad6ce40e1582c847db3d72603f00c4263f608ac1 SHA-256: 1553df040aa4a4cac251d0f6da12b035d9da83e34934d5cbdcf5348404b0c520
242 Risk Score

Malware Insights

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

This Excel 4.0 macro-enabled workbook contains an Auto_Open macro that uses the RUN and CALL functions to execute code. The script concatenates strings to form API calls, including 'Shell32.dll' and 'CryptAcquireContextA', suggesting it is designed to download and execute a second-stage payload. The embedded URL 'https://ctxpress.com/ds/261120.gif' is likely part of this download mechanism.

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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