Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 40fc359d9e81dd32…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:30:17 Authoring application: Microsoft Excel
MD5: 780f9b7ecc86bfc876c3a07b65bde39e SHA-1: 7b0ddf2ba49df2c9599d23468639fe53259de694 SHA-256: 40fc359d9e81dd32583766a1d1f66284d822ebc75a11b31c66b8da9271227d34
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 function, which is a critical finding. This indicates the file is designed to automatically execute code upon opening. The presence of dangerous formula APIs like RUN suggests the macro is intended to download and execute a secondary payload, a common technique for malware 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
e2b13f951399643df2b2ba5e4a0c64270d784e1b3fe17d18b7b5544789be8ec9		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6627 bytes

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