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

Static analysis result for SHA-256 0c5afa8f8ac5407a…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:42:42 Authoring application: Microsoft Excel
MD5: 013741a336579f562a227876bb35adf5 SHA-1: 603d5fc27a8e734a71fbfd6d3b95e13d5023f1ba SHA-256: 0c5afa8f8ac5407a6c8124728848aa21a6fa84ae55cbef4c4264909feb6ca048
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 (XLM) macros, specifically an Auto_Open defined name, which is a known method for executing malicious code upon opening the workbook. The presence of dangerous formula APIs like RUN indicates an intent to execute arbitrary commands, likely to download and run a second-stage payload. No specific family could be identified from the available evidence.

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
eb82905b3fa214050c9a65e4f2c116dbfa3245b16ea79198a5e5f7aa5cfcfa56		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6537 bytes

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