Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 7eb7ac42aeb26f76…

MALICIOUS

Office (OOXML)

436.1 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 61386000759f425d30c33b870f445b46 SHA-1: d7de5cd418cfe76099b6c69270039d83ada47fa2 SHA-256: 7eb7ac42aeb26f76c67b4c2ebdc6502a3990b35cbf5eed2af7bedd31256dab51
208 Risk Score

Malware Insights

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

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' indicates an obfuscated auto-exec VBA loader. The WorkBook_Open macro uses CreateObject to execute a command. This command appears to be constructing a path using environment variables and sheet cell values, likely to download and execute a second-stage payload. The reconstructed command involves 'mshta' and 'Wscript.Shell' to execute a script file located in the ALLUSERSPROFILE directory.

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
b345fee54976076b8f04b2c1643cbd469b759d3d87ec7d5dd258909bde23ca97		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1170 bytes
vbaProject_00.bin
4d25a7d1fa9d189c25b360bbf1e91bfc0a6c8f8580f6e1d5ab88a70100bb7d24		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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