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

Static analysis result for SHA-256 6f1907b45a594f7d…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:43:19 Authoring application: Microsoft Excel
MD5: 2f40757499b0758e58132d9e133be50c SHA-1: 558dd643e6d07adf443eeb8f019aa9c57c676b25 SHA-256: 6f1907b45a594f7d274c13483a997fa3556f9f0d0087e3e02eb94d91f2e6a6c7
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open defined name, which is a common technique for executing malicious code upon opening the workbook. The macro sheet contains dangerous formula APIs, specifically the RUN function, suggesting it is designed to execute a payload. The absence of document body text means the specific lure cannot be determined, but the macro execution is the primary threat.

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
da8eb10472679ef9bb00dcccd1040443e2313b29adb3e7983ddbb4874f1f4321
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6589 bytes