Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 9874e8d3dc579e53…

MALICIOUS

Office (OOXML)

443.6 KB Created: 2000-04-13 21:48:14 UTC Authoring application: Microsoft Excel 12.0000
MD5: 3432967c7bdd3c925aaff75421d39757 SHA-1: b417178c2d31f63c4aebccb3187b925abb5cfd16 SHA-256: 9874e8d3dc579e5310ed86659505dff0567d415a90619ff63c35af2954e2fef5
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel document containing an obfuscated Workbook_Open VBA macro. This macro uses CreateObject to execute a command that appears to download and run a script. The script constructs a command line using mshta and Wscript.Shell, likely to fetch and execute a second-stage payload from a remote source. The obfuscated nature and the use of auto-execution routines suggest a downloader or initial access mechanism.

Heuristics 6

  • 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.
  • 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
62f48d611e8adc6b5670088a9e6b1ce716407092b8ffa892132222fbefa95d13		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1168 bytes
vbaProject_00.bin
b211ebf98208465341508732df7f4fa942ce1966430d2f0fa637e8353d39ca99		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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