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

Static analysis result for SHA-256 8c0215de53590798…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:28:35 Authoring application: Microsoft Excel
MD5: 6bf627bc1d4ddcbe07628ed143c1e0a4 SHA-1: ffd891a4f336666af6d38799a0ac59c688afedf9 SHA-256: 8c0215de535907983e42614b145c3caba153db1a20d07a9f71e6bb7149db9eb8
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1569.002 Shell Execution

The file contains Excel 4.0 (XLM) macros, specifically an Auto_Open defined name, which is a critical heuristic firing. This indicates that the macro will execute automatically upon opening the workbook. The presence of dangerous formula APIs like RUN further suggests that the macro is designed to execute arbitrary commands. While the specific commands are not fully detailed in the provided output, the Auto_Open function is a common technique for downloading and executing 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
09b50aabfd858440615a43792c58ea78ce7043d2db46f1c164122832dd73226c
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6419 bytes