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

Static analysis result for SHA-256 3aef2a4b81226306…

MALICIOUS

Office (OLE) / .XLSX

44.0 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: 02ff26f27da04278e101bdde5ea221e6 SHA-1: acf39cdb40213f1346b8d5448d0a1fb4d1762bdd SHA-256: 3aef2a4b812263069f6f603e21dafeb433a4d22d3a744b85aed4196aceb89232
180 Risk Score

Malware Insights

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

The sample contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates the macro is designed to execute commands. Additionally, environment evasion techniques were detected, suggesting the macro attempts to detect and bypass security measures before execution. The document body contains a large amount of seemingly random text, likely used to obscure the macro's true purpose or to fill the document.

Heuristics 4

  • 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.
  • XLM Auto_Open environment-evasion HALT gate high OLE_XLM_ENVIRONMENT_EVASION_HALT
    Excel 4.0 macro sheet auto-executes multiple GET.WORKSPACE / GET.WINDOW environment checks and halts execution when the host does not match the expected user environment. This is a common sandbox-evasion pattern in XLM malware and is stronger than a bare XLM macro-sheet indicator.
  • 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
c1b2ee33b15a98b345d472b2c3d95ffe68116123079eaa84f2b32e986c89f453		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 13305 bytes

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