A Security Vulnerability in the vncviewer(1) RFB Protocol Validation May Allow Execution of Arbitrary Code and Lead to a Denial of Service (DoS)

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A Security Vulnerability in the vncviewer(1) RFB Protocol Validation May Allow Execution of Arbitrary Code and Lead to a Denial of Service (DoS)

1. Impact

The VNC viewer for X (vncviewer(1)) contains a security vulnerability within the validation function for the server-supplied RFB protocol data that may allow a remote unprivileged user to execute arbitrary code with the privileges of the local user and crash the viewer.  The ability to crash the VNC viewer is a type of Denial of Service (DoS).

This issue is described in the following documents:



2. Contributing Factors

This issue can occur in the following releases:

SPARC Platform

• Solaris 10 5/08 or 10/08 without patch 140455-01
• OpenSolaris based upon builds snv_78 through snv_104
  

x86 Platform

• Solaris 10 5/08 or 10/08 without patch 140456-01
• OpenSolaris based upon builds snv_78 through snv_104

1. Solaris 8 and 9 do not ship with the VNC Viewer software and are therefore not impacted by this issue.

2. Only OpenSolaris installations including the affected binary /usr/bin/vncviewer, are impacted by this issue.

3. OpenSolaris distributions may include additional bug fixes above and beyond the base build from which it was derived.  The base build can be derived as follows:

$ uname -a
SunOS osolsys 5.11 snv_86 i86pc i386 i86pc

3. Symptoms

There are no predictable symptoms that would indicate this issue has been exploited to execute arbitrary code.

In a Denial of Service occurrence, vncviewer(1) will exit prematurely and may generate an error message that references a segmentation violation and may also create a core(4) file.

4. Workaround

To avoid this issue until patches can be applied, connect only to trusted VNC servers.

5. Resolution

This issue is addressed in the following releases:

SPARC Platform

• Solaris 10 with patch 140455-01 or later
• OpenSolaris based upon builds snv_105 or later
  

x86 Platform

• Solaris 10 with patch 140456-01 or later
  
• OpenSolaris based upon builds snv_105 or later
  

For more information on Security Sun Alerts, see Technical Instruction ID 213557.

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