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

Static analysis result for SHA-256 9b9b7c35a2acb51e…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:44:32 Authoring application: Microsoft Excel
MD5: f39b22cc8a841eb6f46b725928dbe902 SHA-1: 163dd92bc58aaa9a8d19ba73422a51485e8b9a5e SHA-256: 9b9b7c35a2acb51ebff75ba14d9f2533777767dd444939214bbb9474f504dfa6
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical heuristic finding. This indicates that the macro will execute automatically when the workbook is opened. The presence of dangerous formula APIs like RUN further confirms the malicious intent to execute arbitrary commands. No specific malware family is identifiable from the provided evidence.

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
7e9e4f61221677d5d926928d6f86dad2a9a77b5289264f8ecbe672dd9c4e2b40		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6684 bytes

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