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

Static analysis result for SHA-256 0ef0a4a88fbfdbaa…

MALICIOUS

Office (OLE) / .XLS

331.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 9a60d6e406fbda15b2d29ef0ed3b2568 SHA-1: 67828fddf6893d90e720f0da7d80c1d844b3233a SHA-256: 0ef0a4a88fbfdbaa902cc067ae29c066865e7156828eceac776a9b451d498b28
242 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros with an Auto_Open entry, which is a critical finding. The macros utilize dangerous functions like RUN and CALL, and specifically the CALL function is used to construct and execute commands. One such command reconstructs to 'CALL(URn,URneA,IICCII,0, DocuSig!FE100, DocuSig!BN62& DocuSig!BN77& DocuSig!BN91,0,0)', indicating it likely downloads and executes a second-stage payload from the embedded URL.

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://zerones.biz/ds/261120.gif
    • https://zerones.biz/ds/261120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
7fbdfe5319125c7a88728c7d99286583a9907fcc6c0161898412d727b081f128		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6676 bytes

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