Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 874d613ee75aeb0f…

MALICIOUS

Office (OOXML)

437.5 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 4c97b3455131425a05e0a94263e1498d SHA-1: 24b9797bc8acf87018d192d0921cd2736f3bd91f SHA-256: 874d613ee75aeb0fea5a1d7d95e0ab6ca25e942be219c1598f619d2738293ee6
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an Excel document containing obfuscated VBA macros designed to execute malicious code. The WorkBook_Open macro uses CreateObject to execute a command that appears to download and run a script file named 'getPercent0895.sct' from the ALLUSERSPROFILE directory using mshta. This indicates a downloader or dropper functionality.

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
8fc695bc4ae32aea3d94807bd8f29b694c05310924678cb79558d2d71603a703		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1091 bytes
vbaProject_00.bin
38a4ce37efce98a05d03a3de26811b88628d2648fea26a2c2201406e0d3edd51		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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