Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 7f7d2a72d173c965…

MALICIOUS

Office (OLE)

434.8 KB Authoring application: Microsoft Excel First seen: 2015-10-05
MD5: b7bc45647186b6efd9b31907be20333e SHA-1: 317eca85ec99b3f4b6e21bc1e36bcb13cf6b9d61 SHA-256: 7f7d2a72d173c965b9f4d4da961ee9d3c16e3410d432e3f87e3d6002785eeb15
162 Risk Score

Heuristics 5

  • XOR-encoded strings (key 0xDE) critical SC_XOR_ENCODED
    Found 5 Windows library/API name(s) XOR-encoded with single-byte key 0xDE: 'GetProcAddress', 'CreateProcessA', 'ExitProcess', 'CreateFileA', 'CreateFileW'
    Disassembly hidden — these bytes score as data, not coherent x86 code (no internal branches to corroborate control flow).
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 445,209 bytes but its declared streams total only 240,528 bytes — 204,681 bytes (46%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOAD
    OLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • VBA project contains no executable statements info OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 606 bytes
SHA-256: 481031c20227961d1e7d207d0bb17c79a9001efbdb37ac509a4ff93acb047bf0
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

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