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

Static analysis result for SHA-256 a3593fb7e5fa0eda…

MALICIOUS

Office (OLE) / .XLSX

44.5 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: 8314722ca0a38f3b9fc1a9dea926e2bf SHA-1: d8c9e94a2cdadfb8ffe88fc4d4f5fa05ed5e67f3 SHA-256: a3593fb7e5fa0edac70c519665db5323e708569055ab5717cc7b4ade40216db1
180 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known method for executing malicious code. The heuristics indicate the presence of dangerous API calls and environment evasion techniques within the macro. While no specific payload or URL was extracted, the presence of the Auto_Open macro strongly suggests an intent to execute arbitrary code upon opening 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
cf8de5b0ca1ae41c82f7e748a167b5774499b59dee448c4e4e02ee4beeb1d4ad		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 13913 bytes

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