Vigil@nce: Checkpoint VPN-1, obtaining the private IP address
November 2008 by Vigil@nce
SYNTHESIS
An attacker can obtain the private IP address of services with a
PAT address translation.
Gravity: 1/4
Consequences: data reading
Provenance: intranet client
Means of attack: no proof of concept, no attack
Ability of attacker: expert (4/4)
Confidence: unique source (2/5)
Diffusion of the vulnerable configuration: high (3/3)
Creation date: 18/11/2008
IMPACTED PRODUCTS
– CheckPoint VPN-1
DESCRIPTION
The Checkpoint VPN-1 firewall can be configured to translate some
ports (PAT, Port Address Translation) to internal computers with a
private IP address. The port 18264/tcp is typically configured
with PAT to reach the Firewall Management Server.
The TTL field of an IP packet indicates the number of routers that
a packet can cross. This number is decremented on each router.
When it reaches zero, an ICMP error message is sent back to the
source. This ICMP message contains the beginning of the failed
packet.
However, when the TTL reaches zero on the firewall, the returned
ICMP packet contains the private IP address instead of the IP
address of the firewall.
An attacker can thus obtain the IP address of services translated
with PAT.
CHARACTERISTICS
Identifiers: BID-32306, VIGILANCE-VUL-8255