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

Static analysis result for SHA-256 214a485eff6b08f8…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:27:07 Authoring application: Microsoft Excel
MD5: c2b33af99c237460dcd1fda6587b1bfb SHA-1: de4b0db3806601102817f06eb9fae0fd66f4eb7b SHA-256: 214a485eff6b08f8757dd60bcb7441d09aeb52974bd727237840cd6b1fcb8169
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1566.001 Spearphishing Attachment

The file contains critical Excel 4.0 macro heuristics, specifically an Auto_Open defined name and the use of dangerous formula APIs like RUN. This indicates the macro sheet is designed to execute commands upon opening the workbook. The presence of the Auto_Open function strongly suggests an attempt to download and execute a second-stage payload. The document body contains obfuscated text, which is typical for lures in macro-based attacks.

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
55b8c56c6e9cf10e87696f9173dbe0514a71ceb8aebb16a1742ce9c401f3db2a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6451 bytes

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