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

Static analysis result for SHA-256 43bfc2bdc879870e…

MALICIOUS

Office (OLE) / .XLS

153.0 KB Created: 2020-04-23 12:26:24 Authoring application: Microsoft Excel
MD5: 888fb4eb15b266e4852444bf62d592e6 SHA-1: 7c86176f30bf38ac5a59fa25ef2393b75cfd9053 SHA-256: 43bfc2bdc879870e4af04eb392356197d2b9f9830f22281038389e841e96fd48
100 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an encrypted Excel 4.0 macro sheet, indicated by the OLE_XLM_ENCRYPTED_MACROSHEET heuristic. The presence of an AutoOpen macro (OLE_XLM_AUTOOPEN) suggests it's designed to execute automatically upon opening. The extensive list of macro sheets in the document properties further supports its nature as a macro-laden document. The document body is heavily obfuscated and truncated, preventing a detailed analysis of its specific payload or delivery mechanism.

Heuristics 3

  • Encrypted Excel 4.0 macro sheet high OLE_XLM_ENCRYPTED_MACROSHEET
    Workbook contains an Excel 4.0 macro sheet and BIFF FILEPASS encryption. Password-protected XLM macro sheets, especially the default Excel password path, are a common malware evasion pattern because static formula extraction may fail until the workbook is decrypted.
  • OLE metadata lists many Excel 4.0 macro sheets high OLE_XLM_DOCPROPS_MACROSHEET_INVENTORY
    Workbook contains a BIFF Excel 4.0 macro-sheet marker and its clear OLE DocumentSummaryInformation stream lists many MacroN sheet titles. This is a useful static signal when FILEPASS encryption prevents formula extraction from the workbook stream.
  • 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.

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