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

Static analysis result for SHA-256 da437cb1b81b669e…

MALICIOUS

Office (OLE) / .XLSX

31.0 KB Created: 2021-01-28 13:37:02 Authoring application: Microsoft Excel
MD5: 6782aee2ece2863c78c6b4615dc8b9a0 SHA-1: 1bb9815d3ca8a649901a6bcfbe95bc7575794e0e SHA-256: da437cb1b81b669e7b9d2038f0313695f5b7584dcd47877d846feae354529dda
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The sample is an Excel 4.0 macro sheet that uses an Auto_Open macro, a known technique for executing malicious code upon opening. The document body explicitly prompts the user to enable editing and content, which is a common lure to bypass security measures. The presence of the XLM_DANGEROUS_FN heuristic indicates the macro uses functions like RUN, suggesting it's designed to execute external commands or payloads.

Heuristics 4

  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
2e30c773eddf1ad67483c5ea7e3bded6acb3ed46e69bd5bad6aacf7f9966cf6f
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3462 bytes