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

Static analysis result for SHA-256 7f8bf0539607525c…

MALICIOUS

Office (OLE) / .XLS

36.5 KB Created: 2020-11-27 11:45:06 Authoring application: Microsoft Excel
MD5: 251bfb84070b02e31e0414f31077075d SHA-1: f99ff61fcbe4937715de4f12451babf6724298dc SHA-256: 7f8bf0539607525c2d3bce323cc9a9afe6d597b7c00575334f9f9a4a4ed11a12
140 Risk Score

Malware Insights

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

The sample is an Excel 97-2003 workbook containing an Excel 4.0 macro sheet. The critical heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code when the workbook is opened. The macro sheet contains a call to a dangerous function, likely for downloading and executing a 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
43246f7477cfdc3e490e1d2f536c2115786290a38e3464f00c4052f1d35a990d		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6759 bytes

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