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

Static analysis result for SHA-256 26bfa0e93852a7ec…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:40:01 Authoring application: Microsoft Excel
MD5: 7220df5238b92303bb1ebbbfcbeb509c SHA-1: 423c40c95b984688df5d0f476e1a2d92c178145d SHA-256: 26bfa0e93852a7ecc828acc602a174ea20e9e233d55a38a6f2179e9cb50bc2b0
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. The critical heuristic firings confirm the presence of a dangerous formula API, specifically the RUN function, indicating the macro is designed to execute arbitrary commands. No specific family could be identified, but the technique is common for initial execution.

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
77d2a9ff762fa2874a3a440baf052842ed7e991f00f15343706db63a2891f54c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6607 bytes

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