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

Static analysis result for SHA-256 6fa9e036f2e275d2…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:41:36 Authoring application: Microsoft Excel
MD5: f758e3c1a79edaa57b17491209ee0f61 SHA-1: bffab4faa31bcc6daebd9386305f269be25803f1 SHA-256: 6fa9e036f2e275d2e1b6ced645777c4d02ca80d16e9169787e8bd8b30679aaaf
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, specifically an Auto_Open defined name, which is a common technique for executing malicious code. The macro sheet contains a reference to a dangerous formula API, RUN, suggesting it's designed to execute a payload. The document body contains obfuscated text, likely part of the macro's execution flow or payload.

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
5fbb0dfabfbd1cbb33ec1551a56e1d8a1da0f0e664b20440e2b3c064ae259a77		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6463 bytes

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