Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b11c33ee5fd193e6…

MALICIOUS

Office (OLE)

313.0 KB Created: 2018-07-26 00:26:51 Authoring application: Microsoft Excel
MD5: f70c0885e76e57f37399d54b10f183ad SHA-1: 20548e3304d242789766edfe7c8c7d4e9ccd5b25 SHA-256: b11c33ee5fd193e6548d14c2bde4865d30d6d5fd25135bc258cfd8595ae3695c
288 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1218.009 System Binary Proxy Execution: Mshta T1105 Ingress Tool Transfer

The Workbook_Open macro is heavily obfuscated and uses CreateObject to instantiate Scripting.FilesystemObject and Wscript.Shell. It constructs a path using environment variables and writes a decoded string to a file named //klCylinderCol.sct. This script is then executed via mshta.exe, indicating a likely downloader or initial execution stage.

Heuristics 8

  • 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.
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • Reference to mshta.exe high SC_STR_MSHTA
    Reference to mshta.exe
  • 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 macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
c568482539c312fababfb4328528ef58f7250c1872b7a316e10eafb80bb2a4d6		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 1171 bytes

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