CVE-2019-5516

VMware ESXi (6.7 before ESXi670-201904101-SG and 6.5 before ESXi650-201903001), Workstation (15.x before 15.0.3 and 14.x before 14.1.6), Fusion (11.x before 11.0.3 and 10.x before 10.1.6) updates address an out-of-bounds vulnerability with the vertex shader functionality. Exploitation of this issue requires an attacker to have access to a virtual machine with 3D graphics enabled. Successful exploitation of this issue may lead to information disclosure or may allow attackers with normal user privileges to create a denial-of-service condition on their own VM. The workaround for this issue involves disabling the 3D-acceleration feature. This feature is not enabled by default on ESXi and is enabled by default on Workstation and Fusion.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://www.talosintelligence.com/vulnerability_reports/TALOS-2019-0762
• https://www.vmware.com/security/advisories/VMSA-2019-0006.html