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Privatefirewall Filter Bypass Vulnerability
Secunia Advisory: SA8861
Release Date: 2003-05-27
Last Update: 2003-10-24
Popularity: 6,691 views

Critical:
Not critical
Impact: Security Bypass
Where: From remote
Solution Status: Vendor Patch

Software:Privatefirewall 3.x

Secunia CVSS-2 Score: Available in Secunia business solutions

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Advisory Content (Page 1 of 3)[ 1 ] [ 2 ] [ 3 ]

Description:
A vulnerability has been identified in Privatefirewall, which can be exploited to bypass the filter.

The problem is that Privatefirewall's filter cannot detect neither FIN nor Xmas scans. This can be exploited to bypass the filter and perform a port scan on the system.

The vulnerability has been reported in version 3.0. Other versions may also be affected.

NOTE:
The severity of this vulnerability has been set to "not critical", because Microsoft did not follow the standard defined in RFC 793 when implementing the TCP/IP stack in Windows.

Normally an open port should ignore packets sent by a FIN or Xmas scan and a closed port should reply with a RST packet. However, in Windows an open port does not ignore the request but instead returns a RST packet.

FIN and Xmas scans conducted against a Windows system will therefore always report all ports as closed and will not aid a malicious person in detecting listening services.

Change Page:
[ 1 ] [ 2 ] [ 3 ]



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