The TLS stack in Mono before 3.12.1 makes it easier for remote attackers to conduct cipher-downgrade attacks to EXPORT_RSA ciphers via crafted TLS traffic, related to the "FREAK" issue, a different vulnerability than CVE-2015-0204.

Multiple SSL vulnerabilities were fixed in the Mono TLS implementation.

  - SKIP-TLS problem could be used to client     impersonification. (CVE-2015-2318)

  - A FREAK style SSL protocol downgrade problem was fixed.
    (CVE-2015-2319)

  - The SSLv2 support was disabled. (CVE-2015-2320)

Three issues with Mono's TLS stack are addressed.

CVE-2015-2318

Mono's implementation of the SSL/TLS stack failed to check the order of the handshake messages. Which would allow various attacks on the protocol to succeed. ('SKIP-TLS')

CVE-2015-2319

Mono's implementation of SSL/TLS also contained support for the weak EXPORT cyphers and was susceptible to the FREAK attack.

CVE-2015-2320

Mono contained SSLv2 fallback code, which is no longer needed and can be considered insecure.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Ubuntu 14.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-2547-1 advisory.

    It was discovered that the Mono TLS implementation was vulnerable to the SKIP-TLS vulnerability. A remote     attacker could possibly use this issue to perform client impersonation attacks. (CVE-2015-2318)

    It was discovered that the Mono TLS implementation was vulnerable to the FREAK vulnerability. A remote     attacker or a machine-in-the-middle could possibly use this issue to force the use of insecure     ciphersuites. (CVE-2015-2319)

    It was discovered that the Mono TLS implementation still supported a fallback to SSLv2. This update     removes the functionality as use of SSLv2 is known to be insecure. (CVE-2015-2320)

    It was discovered that Mono incorrectly handled memory in certain circumstances. A remote attacker could     possibly use this issue to cause Mono to crash, resulting in a denial of service, or to obtain sensitive     information. This issue only applied to Ubuntu 12.04 LTS. (CVE-2011-0992)

    It was discovered that Mono incorrectly handled hash collisions. A remote attacker could possibly use this     issue to cause Mono to crash, resulting in a denial of service. This issue only applied to Ubuntu 12.04     LTS. (CVE-2012-3543)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Researchers at INRIA and Xamarin discovered several vulnerabilities in mono, a platform for running and developing applications based on the ECMA/ISO Standards. Mono's TLS stack contained several problems that hampered its capabilities: those issues could lead to client impersonation (via SKIP-TLS), SSLv2 fallback, and encryption weakening (via FREAK).

ID	Name	Product	Family	Severity
83330	SuSE 11.3 Security Update : Mono (SAT Patch Number 10497)	Nessus	SuSE Local Security Checks	high
82161	Debian DLA-176-1 : mono security update	Nessus	Debian Local Security Checks	critical
82074	Ubuntu 14.04 LTS : Mono vulnerabilities (USN-2547-1)	Nessus	Ubuntu Local Security Checks	critical
82000	Debian DSA-3202-1 : mono - security update	Nessus	Debian Local Security Checks	critical

Detections

Analytics

CVE-2015-2319

high

Tenable Plugins

high

critical

critical

critical