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

Static analysis result for SHA-256 667414175815fc56…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:34:26 Authoring application: Microsoft Excel
MD5: ac0af00709beac4a9846733d5a40f8a6 SHA-1: 988fe9a643e5725db4a7857220f1d57a5c88d93e SHA-256: 667414175815fc56a727cdf725c77dd45d946ee906ebceff6797f3c766f3121d
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating automatic execution. The macros utilize dangerous formula APIs, including RUN, suggesting an attempt to execute arbitrary code. The presence of an Auto_Open entry points to a macro-based execution flow, commonly used for initial payload delivery.

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
87a335e213f74eb18e685d787470b637141258e4e15efe4e8fdc5430d737ad45		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6629 bytes

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