Vulnerabilities > CVE-2022-3913 - Improper Certificate Validation vulnerability in Rapid7 Nexpose
Summary
Rapid7 Nexpose and InsightVM versions 6.6.82 through 6.6.177 fail to validate the certificate of the update server when downloading updates. This failure could allow an attacker in a privileged position on the network to provide their own HTTPS endpoint, or intercept communications to the legitimate endpoint. The attacker would need some pre-existing access to at least one node on the network path between the Rapid7-controlled update server and the Nexpose/InsightVM application, and the ability to either spoof the update server's FQDN or redirect legitimate traffic to the attacker's server in order to exploit this vulnerability. Note that even in this scenario, an attacker could not normally replace an update package with a malicious package, since the update process validates a separate, code-signing certificate, distinct from the HTTPS certificate used for communication. This issue was resolved on February 1, 2023 in update 6.6.178 of Nexpose and InsightVM.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Creating a Rogue Certificate Authority Certificate An attacker exploits a weakness in the MD5 hash algorithm (weak collision resistance) to generate a certificate signing request (CSR) that contains collision blocks in the "to be signed" part. The attacker specially crafts two different, but valid X.509 certificates that when hashed with the MD5 algorithm would yield the same value. The attacker then sends the CSR for one of the certificates to the Certification Authority which uses the MD5 hashing algorithm. That request is completely valid and the Certificate Authority issues an X.509 certificate to the attacker which is signed with its private key. An attacker then takes that signed blob and inserts it into another X.509 certificate that the attacker generated. Due to the MD5 collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the attackers' second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority. To make the attack more interesting, the second certificate could be not just a regular certificate, but rather itself a signing certificate. Thus the attacker is able to start their own Certification Authority that is anchored in its root of trust in the legitimate Certification Authority that has signed the attackers' first X.509 certificate. If the original Certificate Authority was accepted by default by browsers, so will now the Certificate Authority set up by the attacker and of course any certificates that it signs. So the attacker is now able to generate any SSL certificates to impersonate any web server, and the user's browser will not issue any warning to the victim. This can be used to compromise HTTPS communications and other types of systems where PKI and X.509 certificates may be used (e.g., VPN, IPSec) .