Vulnerabilities > CVE-2015-4680 - Improper Certificate Validation vulnerability in multiple products

047910
CVSS 5.0 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
PARTIAL
Availability impact
NONE
network
low complexity
freeradius
suse
CWE-295
nessus

Summary

FreeRADIUS 2.2.x before 2.2.8 and 3.0.x before 3.0.9 does not properly check revocation of intermediate CA certificates.

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) .

Nessus

  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_379788F3290011E5A4A5002590263BF5.NASL
    descriptionoCERT reports : The FreeRADIUS server relies on OpenSSL to perform certificate validation, including Certificate Revocation List (CRL) checks. The FreeRADIUS usage of OpenSSL, in CRL application, limits the checks to leaf certificates, therefore not detecting revocation of intermediate CA certificates. An unexpired client certificate, issued by an intermediate CA with a revoked certificate, is therefore accepted by FreeRADIUS. Specifically sets the X509_V_FLAG_CRL_CHECK flag for leaf certificate CRL checks, but does not use X509_V_FLAG_CRL_CHECK_ALL for CRL checks on the complete trust chain. The FreeRADIUS project advises that the recommended configuration is to use self-signed CAs for all EAP-TLS methods.
    last seen2020-06-01
    modified2020-06-02
    plugin id84697
    published2015-07-14
    reporterThis script is Copyright (C) 2015-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/84697
    titleFreeBSD : freeradius -- insufficient CRL application vulnerability (379788f3-2900-11e5-a4a5-002590263bf5)
  • NASL familySuSE Local Security Checks
    NASL idSUSE_SU-2017-1777-1.NASL
    descriptionThis update for freeradius-server fixes the following issues : - CVE-2017-9148: Disable OpenSSL
    last seen2020-06-01
    modified2020-06-02
    plugin id101229
    published2017-07-05
    reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101229
    titleSUSE SLES11 Security Update : freeradius-server (SUSE-SU-2017:1777-1)
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DLA-977.NASL
    descriptionSeveral issues were discovered in FreeRADIUS, a high-performance and highly configurable RADIUS server. CVE-2014-2015 A stack-based buffer overflow was found in the normify function in the rlm_pap module, which can be attacked by existing users to cause denial of service or other issues. CVE-2015-4680 It was discovered that freeradius failed to check revocation of intermediate CA certificates, thus accepting client certificates issued by revoked certificates from intermediate CAs. Note that to enable checking of intermediate CA certificates, it is necessary to enable the check_all_crl option of the EAP TLS section in eap.conf. This is only necessary for servers using certificates signed by intermediate CAs. Servers that use self-signed CAs are unaffected. CVE-2017-9148 The TLS session cache fails to reliably prevent resumption of an unauthenticated session, which allows remote attackers (such as malicious 802.1X supplicants) to bypass authentication via PEAP or TTLS. For Debian 7
    last seen2020-03-17
    modified2017-06-06
    plugin id100623
    published2017-06-06
    reporterThis script is Copyright (C) 2017-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/100623
    titleDebian DLA-977-1 : freeradius security update
  • NASL familySuSE Local Security Checks
    NASL idSUSE_SU-2017-0102-1.NASL
    descriptionThis update of freeradius-server fixes several issues. Security issue fixed : - CVE-2015-4680: Fixed Insufficent CRL application for intermediate certificates (bsc#935573) Non security issues fixed : - Allows FreeRadius Server to start on SUSE Linux Enterprise Server 12 SP2 systems by relaxing a too strict openssl version check. (bsc#1013311) - Fixed radclient error free() invalid pointer (bsc#911886) - Fixed failing rebuild of freeradius-server package (bsc#951404) Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-01
    modified2020-06-02
    plugin id96404
    published2017-01-11
    reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/96404
    titleSUSE SLES12 Security Update : freeradius-server (SUSE-SU-2017:0102-1)