Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b33c8bfc4d9d936a…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:38:21 Authoring application: Microsoft Excel
MD5: 05fc2fe5a617b656c07f2eb1ea41ee0b SHA-1: 404f3316f06b011826fdd96889182ca5de0d1f2f SHA-256: b33c8bfc4d9d936a530ce4c9638b34eaf49fbd4ab70f2f97f549f55637997cbe
140 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 entry, which is a known technique for executing malicious code upon opening the workbook. The heuristics indicate the use of dangerous formula APIs within the Auto_Open macro, suggesting an intent to run arbitrary commands. No specific family could be identified, but the execution method is clear.

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
38d5d9936419c49b33142fa510d897468df55bc5cd228289af8b0c3ed0ccadf0		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6328 bytes

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