A vulnerability, which was classified as critical, has been found in UltraVNC up to 1.2.2.3 (Connectivity Software). Affected by this issue is an unknown functionality of the component VNC Client Mode. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

UltraVNC revision 1207 has multiple out-of-bounds access vulnerabilities connected with improper usage of SETPIXELS macro in VNC client code, which can potentially result in code execution. This attack appears to be exploitable via network connectivity. These vulnerabilities have been fixed in revision 1208.

The bug was discovered 03/01/2019. The weakness was published 03/08/2019 by Pavel Cheremushkin with Kaspersky Lab ICS CERT as KLCERT-19-012: UltraVNC Access of Memory Location After End of Buffer as confirmed advisory (Website). The advisory is available at ics-cert.kaspersky.com. The original advisory by Kaspersky has a very bad quality and consists of contradicting statements (e.g. summary and CVSS vectors). This vulnerability is handled as CVE-2019-8265 since 02/12/2019. The attack may be launched remotely. No form of authentication is required for exploitation. The technical details are unknown and an exploit is not available. The advisory points out:

UltraVNC revision 1207 has multiple out-of-bounds access vulnerabilities connected with improper usage of SETPIXELS macro in VNC client code, which can potentially result code execution. This attack appear to be exploitable via network connectivity. These vulnerabilities have been fixed in revision 1208.

The vulnerability was handled as a non-public zero-day exploit for at least 7 days. During that time the estimated underground price was around $5k-$25k. The advisory illustrates:

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code.

Upgrading to version 1.2.2.4 eliminates this vulnerability. Applying the patch Revision 1208 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version. A possible mitigation has been published 6 days after the disclosure of the vulnerability.

us-cert.gov is providing further details. Similar entries are available at 131509, 131511, 131512 and 131513.

Productinfo

Type

• Connectivity Software

Name

• UltraVNC

Version

• 1.0.4
• 1.0.5
• 1.0.5.1
• 1.0.8.2
• 1.0.9.5
• 1.0.9.6
• 1.0.9.6.2
• 1.1.4
• 1.1.5
• 1.1.8.0
• 1.1.8.3
• 1.1.8.4
• 1.1.8.5
• 1.1.8.6
• 1.1.8.9
• 1.1.9.0
• 1.1.9.1
• 1.1.9.3
• 1.1.9.6
• 1.2.0.1
• 1.2.0.3
• 1.2.0.4
• 1.2.0.5
• 1.2.0.6
• 1.2.0.7
• 1.2.0.9
• 1.2.1.1
• 1.2.1.2
• 1.2.1.6
• 1.2.1.7
• 1.2.2.1
• 1.2.2.2
• 1.2.2.3

License

• open-source

CPE 2.3info

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CPE 2.2info

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