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

Static analysis result for SHA-256 2447040487c6830e…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:44:35 Authoring application: Microsoft Excel
MD5: dad2c01f6deaa1d2e4a6d37cff4fc9b8 SHA-1: 278db2876e20728e23564c8ceecf72a8dc2b9d43 SHA-256: 2447040487c6830e18527258d13ae29ad1dc8ef6eab982c665fa1238ea523712
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of the 'RUN' function within the macro sheet suggests the execution of arbitrary commands. While the exact payload is not directly visible, the macro's structure and the critical heuristic firings strongly indicate it's designed to download and execute a second-stage payload. The sheet name 'XndukUNG' is also extracted as a potential IOC.

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
7a6c83c611dbd59543b7b74880b9c7cedf3f3a7858d558786a08adb7e973ee4c
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6772 bytes