Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 2bd75faf2b8d3a34…

MALICIOUS

Office (OLE)

305.5 KB Created: 2009-03-23 03:28:33 Authoring application: Microsoft Excel
MD5: 0b1f22448176111f72008b7c0be2fde0 SHA-1: 16c3a14d93924f604f1f3aecf00313e77045cb14 SHA-256: 2bd75faf2b8d3a34bd1c3d05f5a340c919986ca06a336b7be72df33c4894782e
240 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file is identified as malicious by ClamAV and exhibits critical heuristic firings indicating the presence of Excel 4.0 macros with an Auto_Open function. This function is configured to execute the 'RUN' command, which is highly suspicious and indicative of a downloader or initial execution stage. The macro likely attempts to write to the registry key HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy to establish persistence, and execute a payload named 'winupdsv.exe'.

Heuristics 5

  • 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: Xls.Trojan.Netsnak-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Trojan.Netsnak-1
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e9bac86970ab06ed9106fb2e9a0b73d5f8aa2668777221214edfa374f3c8b5cc
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 40267 bytes