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

Static analysis result for SHA-256 735bd3b0890314ff…

MALICIOUS

Office (OLE) / .XLS

331.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: b0f75a11fac3f5ed45f65f61458c92ed SHA-1: 8d592e6b537bc571a9f5518d411a820c63ce82e1 SHA-256: 735bd3b0890314ff9a17735c46979f6e234c8ed0d0ae952b0432cd61d0672440
242 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is designed to execute automatically. The macros utilize dangerous functions like RUN and CALL, and construct strings that appear to form URLs for downloading payloads. One macro constructs the string "Ke"& DocuSig!BY80&"l32" and another "Cr"& DocuSig!BY92&"yA", which likely combine to form API calls. The primary IOC is the URL https://5gict.com/ds/261120.gif, which is likely used to fetch a secondary payload.

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://5gict.com/ds/261120.gif
    • https://5gict.com/ds/261120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a172d04deb874bfc5428cadf9fe508e67386f425fa8a97e12d80c959c827f2d9		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6674 bytes

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