Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b145d0cdb01e7560…

MALICIOUS

Office (OOXML)

435.1 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 12bbcdd1171f89c9f7c3ac41a47a0a8f SHA-1: e1d7e88e8bd36943ac5dee9906edbeb2129fd16e SHA-256: b145d0cdb01e75601fa233fe72df56537675ce354fa55a6a2c3279a196224757
248 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1218.004 Client Execution: Mshta T1059.001 PowerShell

The sample contains an obfuscated Workbook_Open VBA macro that executes a second-stage payload. The macro constructs a command using CreateObject("Wscript.Shell") and mshta to execute a script file, likely \getPasteFormulas4863.sct, located in the ALLUSERSPROFILE directory. This indicates a downloader or dropper functionality.

Heuristics 7

  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • Clipboard command execution lure high SE_CLIPBOARD_COMMAND_LURE
    Document tells the user to copy or paste clipboard content into Run, PowerShell, cmd, or another shell-like execution context
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
66b78d2f2d422199f423ec168939368e68c9eb66ddab48839bc7be6fa0a44759		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1171 bytes
vbaProject_00.bin
e514bf318854f4afd21e9093ccc7f7bb7ccf761f27cc4d8c33d01faee2297a08		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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