{"vuid":"VU#144389","idnumber":"144389","name":"TLS implementations may disclose side channel information via discrepancies between valid and invalid PKCS#1 padding","keywords":["ssl","tls","bleichenbacher","side channel","crypto","cryptography"],"overview":"TLS implementations may disclose side channel information via discrepancies between valid and invalid PKCS#1 padding, and may therefore be vulnerable to Bleichenbacher-style attacks. This attack is known as a \"ROBOT attack\".","clean_desc":"CWE-203: Information Exposure Through Discrepancy\nTransport Layer Security (TLS) is a mechanism for a security transport over network connections, and is defined in RFC 5246. TLS may utilize RSA cryptography to secure the connection, and section 7.4.7 describes how client and server may exchange keys. Implementations that don't closely follow the descriptions in RFC 5246 may leak information to an attacker when they handle PKCS #1 v1.5 padding errors in ways that lets the attacker distinguish between valid and invalid messages. An attacker may utilize discrepancies in TLS error messages to obtain the pre-master secret key private RSA key used by TLS to decrypt sensitive data. This type of attack has become known as a Bleichenbacher attack. CERT/CC previously published CERT Advisory CA-1998-07 for this type of attack. Some modern cryptographic implementations are vulnerable to Bleichenbacher-style attacks on TLS. While RFC 5246 Section 7.4.7.1 provides advice in order to eliminate discrepancies and defend against Bleichenbacher attacks, implementation-specific error and exception handling may nevertheless re-introduce message discrepancies that act as a cryptographic oracle for a Bleichenbacher-style attack. More information about the research and affected vendors is available from the researcher's website.","impact":"A remote, unauthenticated attacker may be able to obtain the TLS pre-master secret (TLS session key) and decrypt TLS traffic.","resolution":"Disable TLS RSA Affected users and system administrators are encouraged to disable TLS RSA cyphers if possible. Please refer to your product's documentation or contact the vendor's customer service. Apply an update Some products may have software updates available to address this issue. If an update is available, affected users are encouraged to update product software or firmware. Please see the Affected Vendors list below for more information. Note for developers RFC 5246 contains remediation advice for Bleichenbacher-style attacks. Developers are encouraged to review the advice and ensure implementations of TLS or software that utilizes a TLS library does not introduce further message or timing discrepancies that may be used in a Bleichenbacher-style attack.","workarounds":"","sysaffected":"The Vendor Information section below lists implementations","thanks":"Thanks to Hanno Boeck Juraj Somorovsky of Ruhr-Universität Bochum / Hackmanit GmbH, and Craig Young of Tripwire VERT\n fo\nr reporting this vulnerability.","author":"This document was written by Garret Wassermann.","public":["https://robotattack.org","https://www.usenix.org/system/files/conference/usenixsecurity14/sec14-paper-meyer.pdf","http://archiv.infsec.ethz.ch/education/fs08/secsem/bleichenbacher98.pdf","https://www.cert.org/historical/advisories/CA-1998-07.cfm","https://tools.ietf.org/html/rfc5246#section-7.4.7.1","http://cwe.mitre.org/data/definitions/203.html"],"cveids":["CVE-2017-6168","CVE-2017-1000385","CVE-2017-17427","CVE-2017-13098","CVE-2017-13099","CVE-2017-17428","CVE-2017-17382","CVE-2012-5081","CVE-2016-6883"],"certadvisory":"","uscerttechnicalalert":null,"datecreated":"2017-11-10T21:36:51Z","publicdate":"2017-12-12T00:00:00Z","datefirstpublished":"2017-12-12T16:04:44Z","dateupdated":"2018-04-09T17:19:13Z","revision":102,"vrda_d1_directreport":"1","vrda_d1_population":"3","vrda_d1_impact":"","cam_widelyknown":"0","cam_exploitation":"0","cam_internetinfrastructure":"0","cam_population":"0","cam_impact":"0","cam_easeofexploitation":"0","cam_attackeraccessrequired":"0","cam_scorecurrent":"0","cam_scorecurrentwidelyknown":"0","cam_scorecurrentwidelyknownexploited":"0","ipprotocol":"","cvss_accessvector":"N","cvss_accesscomplexity":"M","cvss_authentication":null,"cvss_confidentialityimpact":"C","cvss_integrityimpact":"N","cvss_availabilityimpact":"N","cvss_exploitablity":null,"cvss_remediationlevel":"OF","cvss_reportconfidence":"C","cvss_collateraldamagepotential":"ND","cvss_targetdistribution":"M","cvss_securityrequirementscr":"ND","cvss_securityrequirementsir":"ND","cvss_securityrequirementsar":"ND","cvss_basescore":"7.1","cvss_basevector":"AV:N/AC:M/Au:N/C:C/I:N/A:N","cvss_temporalscore":"5.6","cvss_environmentalscore":"4.18360827528","cvss_environmentalvector":"CDP:ND/TD:M/CR:ND/IR:ND/AR:ND","metric":0.0,"vulnote":null}