VBSDownloader — Office (OLE) malware analysis

Static analysis result for SHA-256 3ddac4dc45b86428…

MALICIOUS

Office (OLE)

88.5 KB Created: 2017-09-19 06:24:00 Authoring application: Microsoft Office Word First seen: 2017-10-10
MD5: b140f2c2c48d79b801db7ed0afd68b3e SHA-1: 8af8ab73db3cf3bbf214e25967f63f51c3e9bcb0 SHA-256: 3ddac4dc45b86428cee0c1a038393cc52128015acbecbd3bcfebe79724d1ba50
170 Risk Score

Malware Insights

VBSDownloader · confidence 95%

MITRE ATT&CK
T1059.001 PowerShell T1566.001 Spearphishing Attachment

The sample contains a legacy WordBasic auto-execution macro ('autoopen') and a high-severity heuristic firing for PowerShell references, indicating it is designed to execute a PowerShell payload. ClamAV detection further confirms its malicious nature as a VBSDownloader. The embedded URL is benign and likely a remnant of document templating.

Heuristics 6

  • ClamAV: Doc.Macro.VBSDownloader-6336817-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Macro.VBSDownloader-6336817-0
  • Reference to PowerShell high SC_STR_POWERSHELL
    Reference to PowerShell
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 90,624 bytes but its declared streams total only 45,762 bytes — 44,862 bytes (50%) 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).
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • VBA project contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/drawingml/2006/main In document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 286 bytes
SHA-256: 7771bf99b1125ee0f87040a7dc7c1fa89eec2186bbf4ab3e822c8d665693af47
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

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