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

Static analysis result for SHA-256 a612370e45b7c112…

MALICIOUS

Office (OLE) / .XLS

270.5 KB Created: 2020-04-27 14:46:55 Authoring application: Microsoft Excel
MD5: 890522e2846bc9ae0ee808db164ccdb5 SHA-1: 36b93a892a6f57abec6c40268ff9101ac45a0ca8 SHA-256: a612370e45b7c1121a2ab805c05e67722070d4a9d553d4f1dfb1ddb6f1073567
260 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

This Excel 4.0 macro-enabled workbook contains multiple macro sheets and utilizes the Auto_Open function to execute potentially dangerous formulas. The presence of URLDownloadToFile API calls indicates the macro's intent to download and execute a second-stage payload from a remote source. The heuristics strongly suggest this is a downloader or droppper.

Heuristics 6

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • 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.
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • OLE metadata lists many Excel 4.0 macro sheets medium 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e94878b9b8ad490e92797e5158cf3c0296b51d880b105076f1674dd6e7915a44		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 58300 bytes

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