Cisco TelePresence Video Communication Server…: Cross-Site Request Forgery
CVE-2022-20853 is a high-severity cross-site request forgery vulnerability in Cisco TelePresence Video Communication Server (VCS) Expressway from Cisco, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected Cisco TelePresence Video Communication Server (VCS) Expressway versions: X8.11.2; X8.6; X8.11.3, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.68% chance of exploitation within 30 days, higher than 53% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Cisco TelePresence Video Communication Server (VCS) Expressway you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco TelePresence Video Communication Server (VCS) Expressway | X8.11.2; X8.6; X8.11.3; X8.2.2; X8.8.3; X8.11.0; X12.5.2; X8.1.1; and 32 more ranges | Not stated |
| Cisco | telepresence_video_communication_server_software | x12.5.0; x12.5.1; x12.5.2; x12.5.3; x12.5.4; x12.5.5; x12.5.6; x12.5.7; and 32 more ranges | Not stated |
| Cisco | Telepresence Video Communication Server | x8.1; x8.1.1; x8.1.2; x8.2; x8.2.1; x8.2.2; x8.5; x8.5.1; and 32 more ranges | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:H. Scored by CNA (cisco.com).
Official description
A vulnerability in the REST API of Cisco Expressway Series and Cisco TelePresence VCS could allow an unauthenticated, remote attacker to conduct a cross-site request forgery (CSRF) attack on an affected system. This vulnerability is due to insufficient CSRF protections for the web-based management interface of an affected system. An attacker could exploit this vulnerability by persuading a user of the REST API to follow a crafted link. A successful exploit could allow the attacker to cause the affected system to reload. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Cross-Site Request Forgery
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
How developers prevent this class of flaw
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, use anti-CSRF packages such as the OWASP CSRFGuard. Another example is the ESAPI Session Management control, which includes a component for CSRF.
- Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.
- Generate a unique nonce for each form, place the nonce into the form, and verify the nonce upon receipt of the form. Be sure that the nonce is not predictable (CWE-330).
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
- sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bw-thinrcpt-xss-gSj4CecUNot Applicable
- sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cssm-priv-esc-SEjz69dvNot Applicable
- sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wsa-prv-esc-8PdRU8t8Not Applicable
Other vulnerabilities in Cisco TelePresence Video Communication Server (VCS) Expressway
- 7.0 High severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Cross-Site Request Forgery vulnerabilities
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 8.1 High severity
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