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

Static analysis result for SHA-256 a9c556b2923dccee…

MALICIOUS

Office (OLE) / .XLSX

329.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 38aed6b68acb5f6d0c43c034cc984fe5 SHA-1: 21d3355a08f46d4bb2d902135d56c9a3cc37551d SHA-256: a9c556b2923dcceea4299489ac7404be7f830c4275502d3da2877c0de34ec8ac
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros, specifically an Auto_Open function that utilizes dangerous APIs like RUN. This indicates an attempt to execute arbitrary code. The presence of ShellExecute API calls and an embedded URL pointing to a GIF file on nomzoo.ml strongly suggests the macro is designed to download and execute a second-stage payload. The ClamAV detection further confirms its malicious nature as a downloader.

Heuristics 5

  • 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
  • XLM Auto_Open with dangerous formula APIs high 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.
  • 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://nomzoo.ml/ds/161120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
b74fbb14c9dd0283fe5b35630158622cf58bbddcd03d161d30bf64d1f40271a4		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7889 bytes

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