A vulnerability was found in UltraVNC up to 1.2.2.3 (Connectivity Software). It has been classified as critical. This affects an unknown function of the component VNC Client. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

UltraVNC revision 1203 has out-of-bounds access vulnerability in VNC client inside RAW decoder, which can potentially result code execution. This attack appear to be exploitable via network connectivity. This vulnerability has been fixed in revision 1204.

The bug was discovered 03/01/2019. The weakness was presented 03/08/2019 by Pavel Cheremushkin with Kaspersky Lab ICS CERT as KLCERT-19-009: UltraVNC Access of Memory Location After End of Buffer as confirmed advisory (Website). It is possible to read the advisory 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 uniquely identified as CVE-2019-8280 since 02/12/2019. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The advisory points out:

UltraVNC revision 1203 has out-of-bounds access vulnerability in VNC client inside RAW decoder, which can potentially result code execution. This attack appear to be exploitable via network connectivity. This vulnerability has been fixed in revision 1204.

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 commercial vulnerability scanner Qualys is able to test this issue with plugin 371706 (UltraVNC Multiple Code Execution Vulnerabilities). 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 1204 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.

Further details are available at us-cert.gov. See 131316, 131356, 131357 and 131358 for similar entries.

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

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CPE 2.2info

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