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

Static analysis result for SHA-256 459543867803469c…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:39:25 Authoring application: Microsoft Excel
MD5: 5143db4814f1fbfce21097b0d2424bec SHA-1: 35fcebf57c71032547faa48b24da1285a84c22cd SHA-256: 459543867803469c2725254265f78b5c069341bce6675e9030de0962d054a449
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel 4.0 macro-enabled workbook containing an Auto_Open function. Heuristics indicate the presence of dangerous formula APIs, specifically the RUN function, which allows for the execution of arbitrary commands. The macro sheet itself is obfuscated, but the presence of Auto_Open and the use of the RUN function strongly suggest a malicious intent to execute commands upon opening.

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
8af33b551c3ea1cfa9f64d300cf69ad8ec39bd0776ff662636843f78bc08387b		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6795 bytes

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