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

Static analysis result for SHA-256 139995de8c09aaea…

MALICIOUS

Office (OLE) / .XLS

31.0 KB Created: 2021-01-20 13:00:56 Authoring application: Microsoft Excel
MD5: f60c1468452a212f86cb0d52700ebdd4 SHA-1: d6280b5ed8333de799c02365f3e65099d87be121 SHA-256: 139995de8c09aaea2ed77b97409963f56f3020c5e6b175a2185a89b9822adb7b
140 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled workbook detected with critical heuristics for XLM Auto_Open and dangerous formula APIs. The Auto_Open macro is designed to execute arbitrary commands, likely to download and run a second-stage payload. No specific family could be identified.

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
d95e4135aa20c6a71bb38ca86f94e4f594c2c82bf5075f74e5323c329eee5aec		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3324 bytes

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