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

Static analysis result for SHA-256 4883b678b91c2599…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 17:31:49 Authoring application: Microsoft Excel
MD5: f0f04d75118e78639f97cd5025279ff3 SHA-1: b73ec9b1c60ce6789b460c83116333460fbaa41e SHA-256: 4883b678b91c2599d474ddb057c17c6b67f6e18c3244ba8dbac44bb21797cc4d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an Excel file containing Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristics. The presence of an Auto_Open defined name suggests that the macro will execute automatically upon opening the file. The dangerous formula API 'RUN' was detected, which is commonly used to execute arbitrary commands or download additional payloads. No specific IOCs like URLs or hashes were extracted, but the 'RUN' command itself is a critical indicator of malicious intent.

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
d164e978054930b8ea02b17287fc315cfa24566ef5241abcc7d6d30691cfac39
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6395 bytes