Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 d3da77c7c9a466e7…

MALICIOUS

Office (OLE)

35.5 KB Created: 2020-11-25 10:25:36 Authoring application: Microsoft Excel
MD5: 0c71146a8a6cfeb70dd91047b8714d77 SHA-1: 6c6a51e913556af388973abea4c0041cf92d3a88 SHA-256: d3da77c7c9a466e78a5e63033286a915e767ac6ad72c1ca26e22c2e378d5d46e
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing Excel 4.0 (XLM) macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristics. The presence of an Auto_Open defined name suggests the macro is intended to run automatically when the workbook is opened. The dangerous formula APIs used, specifically RUN, point to the execution of external code, likely a downloader for a second-stage payload.

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
8b88dfa3c3b9f8011af4daafc186d88147ad4fadf6cc5878ebde51faa340d7c1		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6611 bytes

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