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

Static analysis result for SHA-256 d3a531613a5251f0…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:39:38 Authoring application: Microsoft Excel
MD5: a76f312b1ccbfca7f3a6acb622869cb5 SHA-1: 5d888f9505c1269b25abf1048d65dccf7ff79d3d SHA-256: d3a531613a5251f0dd1453e782e3ea88309db3d43f37de0330e9fb346f7cd4c6
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains critical heuristic firings indicating the presence of Excel 4.0 macros, specifically an Auto_Open defined name. The `RUN=0` value associated with the `OLE_XLM_DANGEROUS_FN` heuristic suggests that the macro is designed to execute commands. While the specific commands are not fully extracted, the presence of an Auto_Open macro in an Excel file is a strong indicator of malicious intent, typically used to download and execute further stages.

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
c7752dbefbb1d19597b51ed378266bd3ea571a3851e21bd740f2fd22700bd39f
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6551 bytes