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

Static analysis result for SHA-256 fcea5cf93d635da2…

MALICIOUS

Office (OLE) / .XLS

44.0 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: 99ed815a96da7ba3f79336b7d0d0e538 SHA-1: f8111d806e747099e2aada5c105c0b097f4b14fa SHA-256: fcea5cf93d635da2c1ccde7a6ed9e32dc4fef9aff6fe306afa322a103c59b0f3
180 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled spreadsheet. It contains an Auto_Open defined name, which is a common technique for automatically executing macros when the workbook is opened. The presence of dangerous formula APIs and environment evasion checks suggests malicious intent. The macro sheet itself is heavily obfuscated with random strings, making it difficult to determine the exact payload, but the Auto_Open execution is clear.

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
7e7547393a8a4fcc0e0cbd20c509860873e3100385f28963f7313529b25d1480		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 13635 bytes

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