Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c4acb394a17404e0…

MALICIOUS

Office (OLE)

35.5 KB Created: 2020-11-25 10:46:47 Authoring application: Microsoft Excel
MD5: f8afc42bc0580bcaf35a5deae20af7bc SHA-1: 91fffc3c719bd9274b16b891245d1300bc0e4925 SHA-256: c4acb394a17404e0441a37b483e75e539996ea354153479dcbc44284074276b1
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known method for executing malicious code. The presence of dangerous formula APIs like RUN indicates an intent to execute arbitrary commands. The macro sheet itself is obfuscated, but the Auto_Open entry is clearly identified.

Heuristics 3

  • 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.
  • 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
feec8666e0ca1e1c834360c6f135f5d872d2c7a1ccf6f9d1bde57a4c10f07d0a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6587 bytes

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