Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 09f0cbb8e3c8d594…

MALICIOUS

Office (OOXML) / .XLSM

436.2 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 903fd41a008db40781e160f6a830e2fe SHA-1: f5dcabaf853cb1404a778de06eeb7a44d752c022 SHA-256: 09f0cbb8e3c8d594db9eaf5549421f6725454cee79434720660da3a018a3f801
208 Risk Score

Malware Insights

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

The critical heuristic 'Obfuscated auto-exec VBA loader' and the presence of a Workbook_Open macro indicate malicious intent. The VBA script constructs a path to a script file '%ALLUSERSPROFILE%\getPercentOf7223.sct' and then uses 'mshta' to execute it. This suggests the Excel file acts as a downloader for a second-stage payload.

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
ccfc03d3b80908fc0e7eb24840fa13417fdba29b24a24afa41d273b2e3eb3938		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1148 bytes
vbaProject_00.bin
34109a9f5e6fdffec8824865b58b7778d8da95a695b55f91b35cf006cf16a32b		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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