UltraVNC up to 1.2.2.3 VNC Server insufficient psychological acceptability

Summaryinfo

A vulnerability was found in UltraVNC up to 1.2.2.3. It has been declared as critical. The affected element is an unknown function of the component VNC Server. Such manipulation leads to insufficient psychological acceptability. This vulnerability is uniquely identified as CVE-2019-8277. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in UltraVNC up to 1.2.2.3 (Connectivity Software) and classified as critical. Affected by this issue is some unknown processing of the component VNC Server. The manipulation with an unknown input leads to a insufficient psychological acceptability vulnerability. Using CWE to declare the problem leads to CWE-655. The product has a protection mechanism that is too difficult or inconvenient to use, encouraging non-malicious users to disable or bypass the mechanism, whether by accident or on purpose. Impacted is confidentiality, integrity, and availability. CVE summarizes:

UltraVNC revision 1211 contains multiple memory leaks (CWE-655) in VNC server code, which allows an attacker to read stack memory and can be abused for information disclosure. Combined with another vulnerability, it can be used to leak stack memory and bypass ASLR. This attack appears to be exploitable via network connectivity. These vulnerabilities have been fixed in revision 1212.

The bug was discovered 03/01/2019. The weakness was disclosed 03/08/2019 by Pavel Cheremushkin with Kaspersky Lab ICS CERT as KLCERT-19-024: UltraVNC Improper Initialization 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-2019-8277 since 02/12/2019. The attack may be launched remotely. Required for exploitation is a simple authentication. The technical details are unknown and an exploit is not available. The advisory points out:

UltraVNC revision 1211 contains multiple memory leaks (CWE-655) in VNC server code, which allow an attacker to read stack memory and can be abused for information disclosure. Combined with another vulnerability, it can be used to leak stack memory and bypass ASLR. This attack appear to be exploitable via network connectivity. These vulnerabilities have been fixed in revision 1212.

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 371788 (UltraVNC multiple off-by-one 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 1212 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. The entries VDB-131509, VDB-131510, VDB-131511 and VDB-131512 are pretty similar. If you want to get best quality of vulnerability data, you may have to visit VulDB.

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

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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