CVE-2023-32712

In Splunk Enterprise versions below 9.1.0.2, 9.0.5.1, and 8.2.11.2, an attacker can inject American National Standards Institute (ANSI) escape codes into Splunk log files that, when a vulnerable terminal application reads them, can potentially, at worst, result in possible code execution in the vulnerable application. This attack requires a user to use a terminal application that supports the translation of ANSI escape codes to read the malicious log file locally in the vulnerable terminal, and to perform additional user interaction to exploit. Universal Forwarder versions 9.1.0.1, 9.0.5, 8.2.11, and lower can be vulnerable in situations where they have management services active and accessible over the network. Universal Forwarder versions 9.0.x and 9.1.x bind management services to the local machine and are not vulnerable in this specific configuration. See SVD-2022-0605 for more information. Universal Forwarder versions 9.1 use Unix Domain Sockets (UDS) for communication, which further reduces the potential attack surface. The vulnerability does not directly affect Splunk Enterprise or Universal Forwarder. The indirect impact on Splunk Enterprise and Universal Forwarder can vary significantly depending on the permissions in the vulnerable terminal application and where and how the user reads the malicious log file. For example, users can copy the malicious file from the Splunk Enterprise instance and read it on their local machine.

Weakness

The product does not neutralize or incorrectly neutralizes output that is written to logs.

Affected Software

Extended Description

This can allow an attacker to forge log entries or inject malicious content into logs. Log forging vulnerabilities occur when:

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.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/268.html
• https://cwe.mitre.org/data/definitions/81.html
• https://cwe.mitre.org/data/definitions/93.html

References

• https://advisory.splunk.com/advisories/SVD-2023-0606
• https://research.splunk.com/application/de3908dc-1298-446d-84b9-fa81d37e959b
• https://advisory.splunk.com/advisories/SVD-2023-0606
• https://research.splunk.com/application/de3908dc-1298-446d-84b9-fa81d37e959b