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

Static analysis result for SHA-256 d215b8ce7901abb6…

MALICIOUS

Office (OLE) / .XLSX

77.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-23
MD5: 537a23bbe10f4f0a9a253da4fb90a717 SHA-1: 1ca287625ed8fac1c3e131a965d490110549d3e9 SHA-256: d215b8ce7901abb6f345bacb0f9e59a06b58688f46e3d35d80c0eb3d508c8de6
140 Risk Score

Malware Insights

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

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that uses dangerous functions like RUN. This macro sheet is designed to execute code upon opening the workbook. The extracted URLs are likely used to download and execute a second-stage payload. The confidence is high due to the clear indicators of macro execution, but the exact payload and family are not determined.

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
2ca0966e93dacad101ceb18f4d58731b5432892fe851526f2fda59486181312c
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7325 bytes