TITLE:
Linux Kernel IP ID Value Increment Weakness

SECUNIA ADVISORY ID:
SA19402

VERIFY ADVISORY:
http://secunia.com/advisories/19402/

CRITICAL:
Not critical

IMPACT:
Security Bypass, Exposure of system information

WHERE:
>From remote

OPERATING SYSTEM:
Linux Kernel 2.6.x
http://secunia.com/product/2719/
Linux Kernel 2.4.x
http://secunia.com/product/763/

DESCRIPTION:
Marco Ivaldi has reported a weakness in the Linux kernel, which can
be exploited by malicious people to disclose certain system
information and potentially to bypass certain security restrictions.

The weakness is caused due to an error within the
"ip_push_pending_frames()" function when creating a packet in reply
to a received SYN/ACK packet. This causes RST packets to be sent with
a IP ID value that is incremented per packet. This can potentially be
exploited to conduct idle scan attacks.

The weakness has been reported in the 2.4 and 2.6 kernel branches.

SOLUTION:
Update to version 2.6.16.1.
http://www.kernel.org/

Secunia is currently not aware of any official patches for the 2.4
kernel.

PROVIDED AND/OR DISCOVERED BY:
Marco Ivaldi

ORIGINAL ADVISORY:
Kernel.org:
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.16.1
http://www.kernel.org/git/?p=linux/kernel/git/stable/linux-2.6.16.y.git;a=commit;h=6f78133bf7a06845afee5bcdff7c276bbceaaf55

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