Notifications pour un CVE
Restez informé de toutes modifications pour un CVE spécifique.
Descriptions du CVE
Firewall-1 sets a long timeout for connections that begin with ACK or other packets except SYN, allowing an attacker to conduct a denial of service via a large number of connection attempts to unresponsive systems.
Informations du CVE
Métriques
| Métriques | Score | Gravité | CVSS Vecteur | Source |
|---|---|---|---|---|
| V2 | 2.1 | AV:L/AC:L/Au:N/C:N/I:N/A:P | nvd@nist.gov |
EPSS
EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.
Score EPSS
Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.
Percentile EPSS
Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
Informations sur l'Exploit
Exploit Database EDB-ID : 19436
Date de publication : 1999-07-28 22h00 +00:00
Auteur : Lance Spitzner
EDB Vérifié : Yes
source: https://www.securityfocus.com/bid/549/info
A denial of service condition exists in some implementations of Firewall-1 by Checkpoint Software. This denial of service attack is possible due to the way Firewall-1 handles TCP connections.
Typically to initiate a TCP connection, a SYN packet is sent to the destination host. On systems where Firewall-1 is installed, this packet is first passed through an internal stack maintained by the Firewall before it is passed onto the operating system's native stack. When Firewall-1 filters this packet, it checks it against the rule base. If the session is allowed where it's rulebase is concerned, it is added to the connections table with a timeout of 60 seconds. When the remote host responds with an ACK (Acknowledge) packet, the session is bumped up to a 3600 second timeout.
However, if you initiate a connection with an ACK packet, Firewall-1 compares it against the rule base, if allowed it is added to the connections table. However, the timeout is set to 3600 seconds and does not care if a remote system responds. You now have a session with a 1 hour timeout, even though no system responded. If this is done with a large amount of ACK packets, it will result in a full connections table. This results in your Firewall-1 refusing subsequent connections from any source effectively rendering the Firewall-1 useless in a 'failed closed' state.
Most companies allow http outbound. Run this command as root from an internal system, I give your FW about 10 to 15 minutes. If your internal network is a 10.x.x.x, try 172.16.*.*
nmap -sP 10.*.*.*
nmap is a very powerful port scanner. With this command it does only a PING and TCP sweep (default port 80), but uses an ACK instead of a SYN.
To verify that your connections table is quickly growing, try "fw tab -t connections -s" at 10 second intervals.
Tested on ver 4.0 SP3 on Solaris x86 2.6.
Products Mentioned
Configuraton 0
Checkpoint>>Firewall-1 >> Version 3.0
- Checkpoint>>Firewall-1 >> Version 3.0 (Open CPE detail)
Checkpoint>>Firewall-1 >> Version 4.0
- Checkpoint>>Firewall-1 >> Version 4.0 (Open CPE detail)
