CVE-2025-0676: Moxa tcpdump Privilege Escalation Flaw

CVE-2025-0676 Overview

CVE-2025-0676 is a command injection vulnerability affecting the tcpdump utility bundled with Moxa network products. An authenticated attacker with console access can supply crafted input that the utility passes to the underlying shell without proper sanitization. Successful exploitation allows the attacker to execute arbitrary operating system commands, escalate privileges to root, and maintain persistent control of the device. The flaw is tracked under [CWE-78] (Improper Neutralization of Special Elements used in an OS Command). Compromise of these network devices can disrupt connectivity for downstream industrial and enterprise systems that depend on them.

Critical Impact
Authenticated console users can inject OS commands through tcpdump arguments and obtain a root shell on affected Moxa devices.

Affected Products

Moxa industrial networking devices exposing the tcpdump console utility (see vendor advisory MPSA-259491 for the specific model and firmware list)
Devices reachable over the network where console access is permitted to non-root authenticated users
Downstream systems depending on the affected Moxa device for connectivity

Discovery Timeline

2025-04-02 - CVE-2025-0676 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-0676

Vulnerability Analysis

The vulnerability resides in how the Moxa console wraps the tcpdump packet capture utility. User-supplied arguments are concatenated into a shell command string without neutralizing shell metacharacters. An authenticated user with console privileges can inject characters such as ;, |, `, or $() into the argument stream. The injected payload is then interpreted by the shell rather than by tcpdump itself.

Because tcpdump on these embedded devices typically runs with elevated privileges to access raw packet capture interfaces, any injected command inherits those privileges. The result is a horizontal-to-vertical privilege escalation from a restricted console account to a root shell. With root access, an attacker can modify firmware, alter routing or switching behavior, install persistent backdoors, and disable logging.

Root Cause

The root cause is improper input validation when constructing the OS command line for tcpdump. The console wrapper trusts authenticated user input and forwards it directly to a shell interpreter. The absence of allowlist-based argument validation or use of execve-style argument arrays enables [CWE-78] injection.

Attack Vector

Exploitation requires network reachability to the device management interface and valid credentials for an authenticated console account. The attacker invokes the tcpdump console command and embeds shell metacharacters within an argument that is concatenated into the shell command line. Refer to the Moxa Security Advisory MPSA-259491 for vendor-confirmed technical specifics. No public proof-of-concept exploit code is currently referenced in the CVE record.

Detection Methods for CVE-2025-0676

Indicators of Compromise

Unexpected child processes spawned by the tcpdump process tree, such as sh, bash, nc, wget, or curl
Console session logs containing shell metacharacters (;, |, &&, `, $()) in tcpdump argument strings
New or modified files in writable firmware paths, persistence locations, or /tmp immediately after a tcpdump console invocation
Outbound connections from the Moxa device to unfamiliar IP addresses following authenticated console sessions

Detection Strategies

Forward Moxa device syslog and authentication logs to a central SIEM and alert on tcpdump command invocations containing shell metacharacters
Correlate console login events with subsequent process activity to identify abuse of legitimate accounts
Baseline normal tcpdump usage patterns and flag deviations such as long-running captures with unusual argument structures

Monitoring Recommendations

Monitor authentication logs for repeated or off-hours console logins to Moxa management interfaces
Track outbound network connections from device management IP ranges to detect post-exploitation command-and-control activity
Audit account inventories on affected devices and remove unused or default console accounts

How to Mitigate CVE-2025-0676

Immediate Actions Required

Apply the firmware update referenced in Moxa Security Advisory MPSA-259491 as soon as a maintenance window allows
Restrict management interface access to a dedicated administrative VLAN or jump host
Rotate credentials for all console accounts and remove shared or default accounts
Audit existing devices for indicators of prior exploitation before patching

Patch Information

Moxa has published fixed firmware versions in the MPSA-259491 advisory. Consult the advisory for the exact affected models, fixed firmware versions, and upgrade procedures. Validate firmware integrity using vendor-supplied checksums before deployment.

Workarounds

Limit console access to a small set of trusted administrators and enforce strong, unique passwords
Place management interfaces behind a firewall that only permits connections from authorized administrative hosts
Disable or restrict access to the tcpdump console command for non-administrative roles where the device supports role-based access control
Enable logging of all console commands and review logs for suspicious argument patterns

bash

# Configuration example: restrict management plane access with an ACL
# (adapt to the specific Moxa device CLI syntax)
access-list mgmt-acl permit ip 10.0.10.0 0.0.0.255 any
access-list mgmt-acl deny   ip any any log
interface mgmt0
 ip access-group mgmt-acl in