CVE-2023-20034: Cisco SD-WAN Information Disclosure Flaw

CVE-2023-20034 Overview

CVE-2023-20034 is a hardcoded credentials vulnerability [CWE-798] in the Elasticsearch database component of Cisco SD-WAN vManage software. The flaw allows an unauthenticated, remote attacker to read the Elasticsearch configuration database with the privileges of the elasticsearch user. Exploitation requires only a crafted HTTP request to TCP port 9200 on a reachable vManage instance. Cisco published the security advisory and confirmed that workarounds are available.

Critical Impact
Unauthenticated remote attackers can read sensitive Elasticsearch database contents on Cisco SD-WAN vManage appliances by reaching port 9200, exposing configuration data without any user interaction or credentials.

Affected Products

Cisco SD-WAN vManage (general)
Cisco SD-WAN vManage 20.6
Cisco SD-WAN vManage 20.7

Discovery Timeline

2023-09-27 - CVE-2023-20034 published to the National Vulnerability Database (NVD)
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-20034

Vulnerability Analysis

The vulnerability resides in the Elasticsearch instance bundled with Cisco SD-WAN vManage. Cisco shipped the product with a static username and password configured on the Elasticsearch service. Because the credentials are embedded in the deployed software, every affected vManage instance accepts the same authentication material. An attacker who knows the static credentials, or who can reach the unauthenticated Elasticsearch HTTP API on port 9200, can query the configuration database directly.

The weakness is classified under [CWE-798] Use of Hard-coded Credentials. Successful exploitation impacts confidentiality only — the CVSS vector indicates no impact to integrity or availability. The Elasticsearch database used by vManage stores configuration state for the SD-WAN fabric, so disclosed contents can include device, policy, and topology metadata useful for follow-on attacks against the SD-WAN overlay.

Root Cause

The root cause is a static, vendor-set credential pair embedded in the vManage Elasticsearch configuration. Because the credential material is identical across deployments and cannot be changed by the operator through normal configuration, any attacker with network reachability to port 9200 can authenticate as the elasticsearch user.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. The attacker sends a crafted HTTP request to a vManage management interface on TCP port 9200. If the port is reachable from the attacker's network position, the request returns Elasticsearch database content. The vulnerability is most exploitable when the vManage management plane is exposed beyond a restricted administrative network.

No public proof-of-concept exploit is listed in Exploit-DB, and the issue is not on the CISA Known Exploited Vulnerabilities catalog. See the Cisco Security Advisory for vendor technical details.

Detection Methods for CVE-2023-20034

Indicators of Compromise

Unexpected inbound TCP connections to port 9200 on Cisco SD-WAN vManage interfaces from sources outside the management network.
HTTP requests to Elasticsearch REST endpoints such as /_search, /_cat/indices, or /_cluster/state in vManage access logs.
Authentication events on the Elasticsearch service originating from non-administrator source addresses.

Detection Strategies

Monitor network flows to vManage management addresses and alert on any traffic to port 9200 that does not originate from approved administrative hosts.
Inspect Elasticsearch query logs on vManage for read operations that fall outside the appliance's normal internal query patterns.
Correlate firewall and load-balancer logs to identify external scanning probes targeting Elasticsearch default ports.

Monitoring Recommendations

Enable centralized logging of vManage system and application logs and forward them to a SIEM for retention and correlation.
Baseline legitimate management-plane traffic so that anomalous port 9200 access is immediately visible.
Add IDS or NDR signatures for unauthenticated Elasticsearch REST API requests against SD-WAN management ranges.

How to Mitigate CVE-2023-20034

Immediate Actions Required

Apply the fixed Cisco SD-WAN vManage software versions identified in the Cisco Security Advisory cisco-sa-sdwan-vman-sc-LRLfu2z.
Restrict network access to vManage management interfaces so that only authorized administrative hosts can reach the appliance.
Audit historical access logs for prior connections to port 9200 from unexpected sources.

Patch Information

Cisco addressed CVE-2023-20034 through fixed software releases documented in the Cisco Security Advisory. Operators running vManage 20.6 or 20.7 should consult the advisory's Fixed Software table and upgrade to a release that remediates the hardcoded credential.

Workarounds

Block external access to TCP port 9200 on vManage interfaces using access control lists or upstream firewalls.
Place vManage on an isolated management VLAN and require jump-host access for administrators.
Use control-plane access policies to permit Elasticsearch traffic only from loopback or internal cluster interfaces.

bash

# Example access control to restrict TCP/9200 to an administrative subnet
# Replace 10.10.0.0/24 with your management network
iptables -A INPUT -p tcp --dport 9200 -s 10.10.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 9200 -j DROP