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

Static analysis result for SHA-256 e44c74da5b4c39f3…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:44:58 Authoring application: Microsoft Excel
MD5: 5fb0d5e70f1644546148b8fb5f7f9de1 SHA-1: ef157adcef3772c48fb774edc7b08562e6b87748 SHA-256: e44c74da5b4c39f3f2f82a6c412fd82436ff6406292ef161950ad4390bf4cadd
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1059.001 PowerShell: PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious activity. The presence of the 'RUN=0' function within the macro suggests it is designed to execute commands. While the specific command or payload is not directly visible due to truncation, the overall pattern points to a macro-based execution of a secondary payload. The document body contains seemingly random strings and characters, which could be obfuscation or part of the macro's execution flow.

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
690f771ddf7edb418f1b7d407106d21ca6ef168e9a8fbed55b26efb559c87746
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6501 bytes