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

Static analysis result for SHA-256 5f3753b13dfeeb26…

MALICIOUS

Office (OOXML) / .XLSM

437.9 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 11af5ca9c6eb138c2a00af51b9c80895 SHA-1: 6b56f4474238d232d8b16e3f146554dd8af8ed9f SHA-256: 5f3753b13dfeeb267528ec0d87e7f2ed77333e36bf84f67914e0ed02c736d5d9
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 script, likely a downloader. The script constructs the path '%ALLUSERSPROFILE%\getFixedValue9397.sct' and executes it via mshta, indicating a multi-stage attack.

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
827cc1c3854f1a0574a8fa7a6f45beaf53ac201106687a8de8e1e7f46638ce12		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1153 bytes
vbaProject_00.bin
7364fff9db8fa98c1760e27f60ce18bf7f89b244bd9ddd3b679774dd862ed158		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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