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

Static analysis result for SHA-256 6536fdd415d0f136…

MALICIOUS

Office (OOXML) / .XLSM

435.7 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 97946a5e31378187cae3402a8401639c SHA-1: af0f1d84aeccddfa3d8639c3e9b6019f0e3a6499 SHA-256: 6536fdd415d0f136bde5d9339278326acbcbe3688065ab5bb50d99463c91fbd4
208 Risk Score

Malware Insights

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

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' indicates an obfuscated auto-exec VBA loader that uses CreateObject, Shell, and exec sinks. The Workbook_Open macro is present and uses CreateObject to execute a command. The script constructs a path using Environ() and Cells() which resolves to 'ALLUSERSPROFILE\getMajorGridlines1775.sct' and then executes it via 'mshta' and 'Wscript.Shell'. This suggests the macro is designed to download and execute 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
9f7cb402a1426b8d5d74438128afc8783de53c9162a0972f6c2e55617354f543		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1175 bytes
vbaProject_00.bin
2f574b6c8fc1cac0f425165c5b1d300112eacb8031a45abd7ebf3c675d6f5442		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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