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Authenticated command injection in Web SSH feature

High
tobychui published GHSA-7hpf-g48v-hw3j Nov 12, 2024

Package

gomod github.com/tobychui/zoraxy (Go)

Affected versions

>= 2.6.1, <= 3.1.2

Patched versions

3.1.3

Description

Summary

A command injection vulnerability in the Web SSH feature allows an authenticated attacker to execute arbitrary commands as root on the host.

Details

Zoraxy has a Web SSH terminal feature that allows authenticated users to connect to SSH servers from their browsers.
In HandleCreateProxySession the request to create an SSH session is handled. After checking for the presence of required parameters, ensuring that the target is not the loopback interface and that there is actually an SSH service running on the target, CreateNewConnection is called:

zoraxy/src/mod/sshprox/sshprox.go

Lines 165 to 178 in e79a70b

func (i *Instance) CreateNewConnection(listenPort int, username string, remoteIpAddr string, remotePort int) error {
//Create a gotty instance
connAddr := remoteIpAddr
if username != "" {
connAddr = username + "@" + remoteIpAddr
}
configPath := filepath.Join(filepath.Dir(i.ExecPath), ".gotty")
title := username + "@" + remoteIpAddr
if remotePort != 22 {
title = title + ":" + strconv.Itoa(remotePort)
}
sshCommand := []string{"ssh", "-t", connAddr, "-p", strconv.Itoa(remotePort)}
cmd := exec.Command(i.ExecPath, "-w", "-p", strconv.Itoa(listenPort), "--once", "--config", configPath, "--title-format", title, "bash", "-c", strings.Join(sshCommand, " "))

In line 178, the gotty binary is executed running sshCommand from the line above. It contains the user-controlled variable connAddr, which includes the hostname of the SSH server and - if provided - the username.
An attacker can exploit the username variable to escape from the bash command and inject arbitrary commands into sshCommand. This is possible, because, unlike hostname and port, the username is not validated or sanitized.

This vulnerability was introduced in c07d5f8.
If Zoraxy is run without authentication of the management interface (started with-noauth), this vulnerability can be exploited without authentication.
Additionally, if Zoraxy is run in Docker with the Docker socket mounted (as described in https://github.com/tobychui/zoraxy/blob/9cb315ea6739d1cc201b690322d25166b12dc5db/docker/README.md), this vulnerability can be exploited to escape the Zoraxy container and gain access to the Docker host.

PoC

  1. Download and run Zoraxy as described in the README
  2. Setup a user
  3. Login as user
  4. Navigate to Other -> Network Tools -> Connection
  5. Enter hostname / IP of any server with SSH running, e.g. github.com
  6. Enter ; bash ; as user
  7. Click Connect using SSH
  8. A window will open with bash running on the Zoraxy host

Demo:

poc.mp4

Impact

This vulnerability allows an authenticated attacker to gain remote code execution with the privileges of the Zoraxy process (root by default). This affects Zoraxy versions 2.6.1 through 3.1.2.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required High
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVE ID

CVE-2024-52010

Weaknesses

Credits