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

Static analysis result for SHA-256 ba501741db668d78…

MALICIOUS

Office (OLE) / .XLS

75.5 KB Created: 2020-05-20 08:20:55 Authoring application: Microsoft Excel
MD5: 655a10d0d30b4e33949043617fbb2d63 SHA-1: f8ce0eb0772048b3ff6d1138d70047da2d9e7376 SHA-256: ba501741db668d78072bc28614d49eb61a3b63eb7eda27d5b51a5001bfa0f0c3
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious Link: Malicious File

The critical OLE_XLM_DANGEROUS_FN heuristic indicates the presence of dangerous Excel 4.0 macro functions, specifically RUN. The macro sheet contains a reference to 'http://os.meduarncbx.com/CGVqBLj', which is likely used to download and execute a second-stage payload. The presence of an Auto_Open defined name further confirms the automatic execution of these macros upon opening the document.

Heuristics 3

  • 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.
  • 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
da5422c871b56ed17bc908e58b7d18b5ac013f910fcbb82c04b03b708bb9a143		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 41619 bytes

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