CVE-2017-3599

Vulnerability in the MySQL Server component of Oracle MySQL (subcomponent: Server: Pluggable Auth). Supported versions that are affected are 5.6.35 and earlier and 5.7.17 and earlier. Easily exploitable vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.0 Base Score 7.5 (Availability impacts). CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). NOTE: the previous information is from the April 2017 CPU. Oracle has not commented on third-party claims that this issue is an integer overflow in sql/auth/sql_authentication.cc which allows remote attackers to cause a denial of service via a crafted authentication packet.

Weakness

The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• If possible, choose a language or compiler that performs automatic bounds checking.
• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• Use libraries or frameworks that make it easier to handle numbers without unexpected consequences.
• Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
• Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
• Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values.
• Understand the programming language’s underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, “not-a-number” calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7]
• Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/92.html

References

• http://www.oracle.com/technetwork/security-advisory/cpuapr2017-3236618.html
• http://www.securityfocus.com/bid/97754
• http://www.securitytracker.com/id/1038287
• https://access.redhat.com/errata/RHSA-2017:2787
• https://access.redhat.com/errata/RHSA-2017:2886
• https://www.exploit-db.com/exploits/41954/
• https://www.secforce.com/blog/2017/04/cve-2017-3599-pre-auth-mysql-remote-dos/