# MA-434.122014: MyCERT Advisory - SSL 3.0 Protocol Vulnerability and POODLE Attack

**Date:** 12 Dec 2014  
**Source:** https://www.mycert.org.my/portal/advisory?id=MA-434.122014  
**Advisory ID:** MA-434.122014

---

#### **1.0    Introduction**
It is known that there is a design vulnerability found in the way SSL 3.0 handles block cipher mode padding. The POODLE attack demonstrates how an attacker can exploit this vulnerability to decrypt and extract information from inside an encrypted transaction.
A new variant of the POODLE attack may affect some TLS implementations on account of an issue similar to one present in SSL 3.0. Successful exploitation may enable actors to derive plaintext from encrypted communications.
**2.0    Impact**
- The POODLE attack can be used against any system or application that supports SSL 3.0 with CBC mode ciphers.
- This affects most current browsers and websites, but also includes any software that either references a vulnerable SSL/TLS library (e.g. OpenSSL) or implements the SSL/TLS protocol suite itself.
- By exploiting this vulnerability in a likely web-based scenario, an attacker can gain access to sensitive data passed within the encrypted web session, such as passwords, cookies and other authentication tokens that can then be used to gain more complete access to a website (impersonating that user, accessing database content, etc.).
**3.0 Systems Affected**
- All systems and applications utilizing the Secure Socket Layer (SSL) 3.0 with cipher-block chaining (CBC) mode ciphers may be vulnerable.
- However, the POODLE (Padding Oracle On Downgraded Legacy Encryption) attack demonstrates this vulnerability using web browsers and web servers, which is one of the most likely exploitation scenarios.
- Some Transport Layer Security (TLS) implementations are also vulnerable to the POODLE attack.
**4.0    Recommendation**
Currently, there is no fix for the vulnerability SSL 3.0 itself since this issue is fundamental to the protocol. As for now, disabling SSL 3.0 support in system/application settings is the best solution.
The researchers that discovered the weaknesses has also developed a fix for one of the prerequisite conditions: TLS\_FALLBACK\_SCSV is a protocol extension that prevents MITM attackers from being able to force a protocol downgrade. OpenSSL has added support for this in their latest release and recommends the following update:
- OpenSSL 1.0.1 users should upgrade to 1.0.1j
- OpenSSL 1.0.0 users should upgrade to 1.0.0o
- OpenSSL 0.9.8 users should upgrade to 0.9.8zc
To prevent the downgrade attacks, both server and client need to support TLS\_FALLBACK\_SCSV. Other SSL 3.0 implementations are most likely also affected by POODLE.
MyCERT advises the users of this software to be updated with the latest security announcements by the vendor and follow best practice security policies to determine which updates should be applied.
For further enquiries, please contact MyCERT through the following channels:
E-mail: [[email protected]](/cdn-cgi/l/email-protection) or [[email protected]](/cdn-cgi/l/email-protection)
Phone: 1-300-88-2999 (monitored during business hours)
Fax : +603 89453442
Mobile: +60 19 2665850 (24x7 call incident reporting)
SMS : CYBER999 REPORT EMAIL COMPLAINT to 15888
Business Hours : Mon - Fri 09:00 AM - 18:00 PM MYT
Web: <https://www.mycert.org.my>
Twitter: <http://www.twitter.com/mycert>
Facebook: <http://www.facebook.com/mycert.org.my>
Cyber999 Mobile Apps: [IOS Users](https://itunes.apple.com/my/app/cyber999-mobile-application/id888552400?mt=8&ign-mpt=uo%3D4) or [Android Users](https://play.google.com/store/apps/details?id=my.cyber999.mobile)
**5.0    References**
[1]    US CERT: SSL 3.0 Protocol Vulnerability and POODLE attack [online], <https://www.us-cert.gov/ncas/alerts/TA14-290A>
[2]    OpenSSL Security Advisory [online], <https://www.openssl.org/news/secadv_20141015.txt>
[3]    Certain TLS Implementations Vulnerable to POODLE Attacks, [https://www.us-cert.gov/ncas/current-activity/2014/12/09/Certain-TLS-Implementations-Vulnerable-POODLE-Attacks](https://www.us-cert.gov/ncas/current-activity/2014/12/09/Certain-TLS-Implementations-Vulnerable-POODLE-Attacks )