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

Static analysis result for SHA-256 5a8d31c5c85f4eb3…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:38:38 Authoring application: Microsoft Excel
MD5: a2d6940dbe6ffb19ce80a09e5e52dd81 SHA-1: d05dde3731565a6584b817797cf0b2bd0858a7de SHA-256: 5a8d31c5c85f4eb362a6ae648ce3f94f5eee4ce3896386d0185be1c7e7b2ad9f
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 with an Auto_Open defined name, which is a known method for executing arbitrary code. The `RUN=0` formula API within the macro suggests it is designed to execute a command. While no specific URL or executable was extracted, the primary function appears to be the execution of a secondary 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
9fc32b74d758b5c8f863122af85ff4c340037e13a426592b15bcaee9e058f916		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6631 bytes

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