SB2017020101 - Ubuntu update for GnuTLS

Description

This security bulletin contains information about 6 secuirty vulnerabilities.

1) Security restrictions bypass (CVE-ID: CVE-2016-7444)

The vulnerability allows a remote unauthenticated attacker to bypass security restrictions on the target system.

The weakness exists due to insufficient validation of the serial length of an OCSP response by the gnutls_ocsp_resp_check_crt function in the lib/x509/ocsp.c code. A remote attacker can bypass certificate validation and conduct further attacks.

2) Denial of service (CVE-ID: CVE-2016-8610)

The vulnerability allows a remote unauthenticated user to exhaust memory on the target system.
The weakness is due to improper handling of certain packets by the ssl3_read_bytes() function in 'ssl/s3_pkt.c.
By sending a flood of SSL3_AL_WARNING alerts during the SSL handshake, a remote attacker can consume excessive CPU resources that may lead to OpenSSL library being unavailable.
Successful exploitation of the vulnerability results in denial of service on the vulnerable system.

3) Double free (CVE-ID: CVE-2017-5334)

The vulnerability allows a remote unauthenticated attacker to cause DoS condition on the target system.

The weakness exists due to insufficient validation of user-supplied input by the gnutls_x509_ext_import_proxy function. A remote attacker can send a specially crafted X.509 certificate with Proxy Certificate Information extension present, trigger double free error and cause the application to crash.

Successful exploitation of the vulnerability results in denial of service.

4) Memory corruption (CVE-ID: CVE-2017-5335)

The vulnerability allows a remote unauthenticated attacker to cause DoS condition on the target system.

The weakness exists due to insufficient error checking in the stream-reading functions. A remote attacker can send a specially crafted OpenPGP certificate, trigger memory corruption and cause the application to crash.

Successful exploitation of the vulnerability results in denial of service.

5) Stack-based buffer overflow (CVE-ID: CVE-2017-5336)

The vulnerability allows a remote unauthenticated attacker to cause DoS condition on the target system.

The weakness exists due to improper processing of malicious OpenPGP certificates by the cdk_pk_get_keyid function. A remote attacker can send a specially crafted OpenPGP certificate, trigger stack-based buffer overflow and cause the application to crash.

Successful exploitation of the vulnerability results in denial of service.

6) Heap-based buffer overflow (CVE-ID: CVE-2017-5337)

The vulnerability allows a remote unauthenticated attacker to cause DoS condition on the target system.

The weakness exists due to improper processing of malicious OpenPGP certificates by the read_attribute function. A remote attacker can send a specially crafted OpenPGP certificate, trigger heap-based buffer overflow and cause the application to crash.

Successful exploitation of the vulnerability results in denial of service.

Remediation

Install update from vendor's website.

References

• http://www.ubuntu.com/usn/usn-3183-1/