NGS00118 Technical Advisory: Symantec pcAnywhere Remote Code Execution as SYSTEM

["Research@NGSSecure" <research@xxxxxxxxxxxxx>]

=======
Summary
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Name: Symantec pcAnywhere Remote Code Execution (Preauth) 
Release Date: 30 April 2012
Reference: NGS00118
Discoverer: Edward Torkington <edward.torkington@xxxxxxxxxxxxx>
Vendor: Symantec
Vendor Reference: 
Systems Affected: 

Symantec pcAnywhere 12.5.x
IT Management Suite 7.0 pcAnywhere Solution 12.5.x
IT Management Suite 7.1 pcAnywhere Solution 12.6.x

Risk: Critical
Status: Published

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TimeLine
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Discovered: 14 September 2011
Released: 26 September 2011
Approved: 26 September 2011
Reported: 26 September 2011
Fixed: 24 January 2012
Published: 30 April 2012

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Description
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Symantec pcAnywhere Version 12.5 and below is vulnerable to a remote code 
execution vulnerability. A flaw exists in the authentication component 
listening on TCP port 5631 which does not sufficiently validate user-submitted 
data. 

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Technical Details
=================

It is possible to supply an invalid login that causes heap corruption and an 
object pointer overwrite. We end up in with a reliable overwrite of EAX as 
detailed below:

mov ECX,DWORD PTR DS:[EAX]    
mov EDX,DWORD PTR DS:[ECX+8]
push EAX
call EDX

A reliable overwrite in (non-rebasing/ASLR DLLs) of a fully patched Windows XP 
SP3 was found such that remote command execution can be gained.

As the service restarts indefinitely, a reliable exploit in Windows 7 was also 
developed which effectively brute-forces a valid address to bypass ASLR. 

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Fix Information
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http://www.symantec.com/security_response/securityupdates/detail.jsp?fid=security_advisory&pvid=security_advisory&year=2012&suid=20120124_00

NGS Secure Research
http://www.ngssecure.com