Finding and Fixing SSL RC4 Cipher Suites Supported Vulnerability
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Vulnerabilities in SSL RC4 Cipher Suites is a Medium risk vulnerability that is one of the most frequently found on networks around the world. This issue has been around since at least 1990 but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.

Contents: SSL RC4 Cipher Suites

 

Vital Information on This Issue

 

Vulnerability Name: SSL RC4 Cipher Suites Supported
Test ID: 18008
Risk: Medium
Category: Encryption and Authentication
Type: Attack
Summary:

Multiple vulnerabilities have been found in SSL’s RC4 implementation:

* The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for remote attackers to conduct plaintext-recovery attacks via statistical analysis of ciphertext in a large number of sessions that use the same plaintext.

* The RC4 algorithm, as used in the TLS protocol and SSL protocol, does not properly combine state data with key data during the initialization phase, which makes it easier for remote attackers to conduct plaintext-recovery attacks against the initial bytes of a stream by sniffing network traffic that occasionally relies on keys affected by the Invariance Weakness, and then using a brute-force approach involving LSB values, aka the “Bar Mitzvah” issue.

Impact:  
Solution: Reconfigure the affected application, if possible, to avoid use of RC4 ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser and web server support.
CVE: CVE-2013-2566

CVE-2015-2808

More Information: https://blog.cryptographyengineering.com/2013/03/12/attack-of-week-rc4-is-kind-of-broken-in/

http://cr.yp.to/talks/2013.03.12/slides.pdf

https://www.imperva.com/docs/HII_Attacking_SSL_when_using_RC4.pdf

http://www.isg.rhul.ac.uk/tls/

Nist NVD (CVSS): AV:N/AC:M/Au:N/C:P/I:N/A:N
CVSS Score: 4.3

 

Scanning For and Finding Vulnerabilities in SSL RC4 Cipher Suites

Use of Vulnerability Management tools, like Beyond Security’s beSECURE (Automated Vulnerability Detection Software), are standard practice for the discovery of this vulnerability. The primary failure of VA in finding this vulnerability is related to setting the proper scope and frequency of network scans. It is vital that the broadest range of hosts (active IPs) possible are scanned and that scanning is done frequently. We recommend weekly.

Your existing scanning solution or set of test tools should make this not just possible, but easy and affordable. If that is not the case, please consider beSECURE. Learn more or request a trial.

Penetration Testing (pentest) for this Vulnerability

The Vulnerabilities in SSL RC4 Cipher Suites Supported is prone to false positive reports by most vulnerability assessment solutions. beSECURE is alone in using behavior based testing that eliminates this issue. For all other VA tools security consultants will recommend confirmation by direct observation. In any case Penetration testing procedures for discovery of Vulnerabilities in SSL RC4 Cipher Suites Supported produces the highest discovery accuracy rate, but the infrequency of this expensive form of testing degrades its value. The ideal would be to have pentesting accuracy and the frequency and scope possibilities of VA solutions, and this is accomplished only by beSECURE.

Security Updates on Vulnerabilities in SSL RC4 Cipher Suites Supported

Given that this is one of the most frequently found vulnerabilities, there is ample information regarding mitigation online and very good reason to get it fixed. Hackers are also aware that this is a frequently found vulnerability and so its discovery and repair is that much more important. It is so well known and common that any network that has it present and unmitigated indicates “low hanging fruit” to attackers.

Confirming the Presence of Vulnerabilities in SSL RC4 Cipher Suites Supported

beSECURE is currently testing for and finding this vulnerability with zero false positives. If your current set of tools is indicating that it is present but you think it is probably a false positive, please request a demonstration of beSECURE.

False positive/negatives

The secret killer of VA solution value is the false positive. There was an industry wide race to find the most vulnerabilities, including Vulnerabilities in SSL RC4 Cipher Suites Supported ,and this resulted in benefit to poorly written tests that beef up scan reports by adding a high percentage of uncertainty. This may have sold a lot of systems some years ago, but it also stuck almost all VA solutions with deliberately inaccurate reporting that adds time to repairs that no administrator can afford. Beyond Security did not participate in this race to mutually assured destruction of the industry and to this day produces the most accurate and actionable reports available.

Patching/Repairing this Vulnerability

https://support.microsoft.com/en-us/kb/2868725

Vulnerabilities in SSL RC4 Cipher Suites Supported is a Medium risk vulnerability that is also high frequency and high visibility. This is the most severe combination of security factors that exists and it is extremely important to find it on your network and fix it as soon as possible.

Exploits related to Vulnerabilities in SSL RC4 Cipher Suites Supported

https://www.securityweek.com/new-attack-rc4-based-ssltls-leverages-13-year-old-vulnerability

https://docs.digicert.com/certificate-tools/discovery-user-guide/

 

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