Malicious Office (OLE) — malware analysis report

Heuristics 18

• ClamAV: Doc.Downloader.Generic-6698421-0 critical CLAMAV_DETECTION
  ClamAV detected this file as malware: Doc.Downloader.Generic-6698421-0
• VBA macros detected medium 12 related findings OLE_VBA_MACROS
  Document contains VBA macro code
• Potential Shell call in VBA critical OLE_VBA_SHELL
  Potential Shell call in VBA
  Matched line in script

       retVal = Shell(XPBARTFILEDIR, 0)

• WScript.Shell usage critical OLE_VBA_WSCRIPT
  WScript.Shell usage
  Matched line in script

       Print #FileNumber, "Set objShell = CreateObject(" + Chr(34) + "WScript.Shell" + Chr(34) + ")"

• VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
  VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
  Matched line in script

       Print #FileNumber, "objADOStream.Write objXMLHTTP.ResponseBody "

• Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
  VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  Matched line in script

      Set objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" & ".\root\cimv2")

• CreateObject call high OLE_VBA_CREATEOBJ
  CreateObject call
  Matched line in script

       Print #FileNumber, "Set objADOStream = CreateObject(" + Chr(34) + "ADODB.Stream" + Chr(34) + ") "

• GetObject call high OLE_VBA_GETOBJ
  GetObject call
  Matched line in script

      Set objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" & ".\root\cimv2")

• Payload URL assembled from a Chr()/Asc() string expression (1 URL) high OLE_VBA_EXPR_DROPPER_URL
  A VBA macro builds its stage-2 download URL character by character from string literals concatenated with Chr()/Asc()/StrReverse() results — often nested (Chr(Asc(Chr(Asc("h")))) = "h") and split across the + and & operators, sometimes written out via Print #n, into a second-stage VBScript/PowerShell file. The URL is assembled at run time and never appears contiguously on disk, and there is no numeric array to brute-force, so a literal scan and the array recoverers both miss it. A bounded expression evaluator resolved it; surfaced as an IOC. Self-validating: only a valid host URL that is not already present verbatim in the macro is reported, so a benign macro cannot false-positive.
• 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.
• AutoOpen macro low OLE_VBA_AUTOOPEN
  AutoOpen macro
  Matched line in script

  Sub AutoOpen()

• Workbook_Open macro low OLE_VBA_WBOPEN
  Workbook_Open macro
  Matched line in script

  Sub Workbook_Open()

• Auto_Open macro low OLE_VBA_AUTO
  Auto_Open macro
  Matched line in script

  Sub Auto_Open()

• Environ() call (env variable access) low OLE_VBA_ENVIRON
  Environ() call (env variable access)
  Matched line in script

       USER = Environ("username")

• Reference to Windows Script Host high SC_STR_WSCRIPT
  Reference to Windows Script Host
• 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.
• Macro/content-enable lure medium SE_ENABLE_LURE
  Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
• 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://www.biomobility.com Referenced by macro

  • http://www.biomobility.com/purchase.htmReferenced by macro
  • http://www.biomobility.comE-mailReferenced by macro
  • http://www.2fs.com.au/tmp/rkn.exeReferenced by macro
  • http://office365.com/Referenced by macro
  • http://schemas.openxmlformats.org/drawingml/2006/mainReferenced by macro

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