#VU33290 Security Features in OpenSSL - CVE-2015-1793

Vulnerability identifier: #VU33290

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2015-1793

CWE-ID: CWE-254

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
OpenSSL
Server applications / Encryption software

Vendor: OpenSSL Software Foundation

Description

The vulnerability allows a remote non-authenticated attacker to read and manipulate data.

The X509_verify_cert function in crypto/x509/x509_vfy.c in OpenSSL 1.0.1n, 1.0.1o, 1.0.2b, and 1.0.2c does not properly process X.509 Basic Constraints cA values during identification of alternative certificate chains, which allows remote attackers to spoof a Certification Authority role and trigger unintended certificate verifications via a valid leaf certificate.

Mitigation
Install update from vendor's website.

Vulnerable software versions

OpenSSL: 1.0.1n

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External links
https://fortiguard.com/advisory/2015-07-09-cve-2015-1793-openssl-alternative-chains-certificate-forgery
https://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2015-008.txt.asc
https://kb.juniper.net/InfoCenter/index?page=content&id=JSA10694
https://lists.fedoraproject.org/pipermail/package-announce/2015-July/161747.html
https://lists.fedoraproject.org/pipermail/package-announce/2015-July/161782.html
https://marc.info/?l=bugtraq&m=143880121627664&w=2
https://marc.info/?l=bugtraq&m=144370846326989&w=2
https://openssl.org/news/secadv_20150709.txt
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20150710-openssl
https://www.fortiguard.com/advisory/2015-07-09-cve-2015-1793-openssl-alternative-chains-certificate-forgery
https://www.oracle.com/technetwork/security-advisory/cpuapr2016v3-2985753.html
https://www.oracle.com/technetwork/security-advisory/cpujul2016-2881720.html
https://www.oracle.com/technetwork/security-advisory/cpuoct2016-2881722.html
https://www.oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html
https://www.oracle.com/technetwork/topics/security/bulletinjul2015-2511963.html
https://www.oracle.com/technetwork/topics/security/cpujan2016-2367955.html
https://www.oracle.com/technetwork/topics/security/cpuoct2015-2367953.html
https://www.securityfocus.com/bid/75652
https://www.securityfocus.com/bid/91787
https://www.securitytracker.com/id/1032817
https://www.slackware.com/security/viewer.php?l=slackware-security&y=2015&m=slackware-security.561427
https://www1.huawei.com/en/security/psirt/security-bulletins/security-advisories/hw-454058.htm
https://git.openssl.org/?p=openssl.git;a=commit;h=9a0db453ba017ebcaccbee933ee6511a9ae4d1c8
https://h20564.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c04822825
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05045763
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05184351
https://help.ecostruxureit.com/display/public/UADCO8x/StruxureWare+Data+Center+Operation+Software+Vulnerability+Fixes
https://kc.mcafee.com/corporate/index?page=content&id=SB10125
https://security.gentoo.org/glsa/201507-15
https://www.exploit-db.com/exploits/38640/
https://www.freebsd.org/security/advisories/FreeBSD-SA-15:12.openssl.asc

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.