CAPEC-40
Manipulating Writeable Terminal Devices
This attack exploits terminal devices that allow themselves to be written to by other users. The attacker sends command strings to the target terminal device hoping that the target user will hit enter and thereby execute the malicious command with their privileges. The attacker can send the results (such as copying /etc/passwd) to a known directory and collect once the attack has succeeded.
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Explain the attack pattern CAPEC-40: Manipulating Writeable Terminal Devices: how it unfolds, what it needs and how to prevent and detect it in my systems. Use https://capec.mitre.org/data/definitions/40.html and https://cve.bz/cve/capec/40?via=ask-ai-copy, which lists recent CVEs with the weaknesses it exploits. Cite the sources.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this attack pattern's id and public links.
How the attack unfolds
Explore
The attacker looks for a way in.
[Identify attacker-writable terminals] Determine if users TTYs are writable by the attacker.
2 techniques
- Determine the permissions for the TTYs found on the system. Any that allow user write to the TTY may be vulnerable.
- Attempt to write to other user TTYs. This approach could leave a trail or alert a user.
Exploit
They carry out the attack.
[Execute malicious commands] Using one or more vulnerable TTY, execute commands to achieve various impacts.
1 technique
- Commands that allow reading or writing end user files can be executed.
Prerequisites
User terminals must have a permissive access control such as world writeable that allows normal users to control data on other user's terminals.
Skills required
- Low skill
Ability to discover permissions on terminal devices. Of course, brute force can also be used.
Resources required
Access to a terminal on the target network
Consequences
| Impact | Affects | Note |
|---|---|---|
| Gain Privileges | Confidentiality, Access Control, Authorization | |
| Read Data | Confidentiality | |
| Execute Unauthorized Commands | Confidentiality, Integrity, Availability | Run Arbitrary Code |
Mitigations
Design: Ensure that terminals are only writeable by named owner user and/or administrator
Design: Enforce principle of least privilege
Weaknesses it exploits
- CWE-77 Improper Neutralization of Special Elements used in a Command
Recent CVEs with these weaknesses
- 8.8CVE-2026-12573
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A vulnerability was found in Chengdu Feiyuxing Technology VW2100 and VEC10GP 1.0 B-MB3W202-210825-r11775. This issue affects the function add_expmac of the file var/html/webserver of the component Web Administration Interface. The manipula…
- 9.3CVE-2026-124580
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- 8.8CVE-2026-116786
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FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. Prior to 1.11.3, sofia_presence_handle_sip_i_message() s…
- 8.8CVE-2026-82413
ntopng is a web-based network traffic monitoring application. Prior to 6.7.260717, scripts/lua/rest/v2/add/host/to_scan.lua and scripts/lua/rest/v2/exec/host/schedule_vulnerability_scan.lua accept scan_ports from any authenticated session,…
- 5.5CVE-2026-123022
A vulnerability was detected in agentscope-ai AgentScope up to 2.0.11. The impacted element is the function subprocess.Popen of the file src/agentscope/mcp/_config.py of the component MCP Workspace API. The manipulation of the argument com…
The newest records naming one of them. Each weakness's page lists them all.
Related attack patterns
- Part of
- CAPEC-248 Command Injection
Examples
"Any system that allows other peers to write directly to its terminal process is vulnerable to this type of a…
"Any system that allows other peers to write directly to its terminal process is vulnerable to this type of attack. If the terminals are available through being over-privileged (i.e. world-writable) or the attacker is an administrator, then a series of commands in this format can be used to echo commands out to victim terminals.
"$echo -e "\033[30m\033\132" > /dev/ttyXX
where XX is the tty number of the user under attack. This will paste the characters to another terminal (tty). Note this technique works only if the victim's tty is world writable (which it may not be). That is one reason why programs like write(1) and talk(1) in UNIX systems need to run setuid." [REF-1]
If the victim continues to hit "enter" and execute the commands, there are an endless supply of vectors available to the attacker, copying files, open up network connections, ftp out to servers, and so on.
MITRE's words, unchanged: CAPEC-40 at MITRE. CAPEC is Copyright © 2007–2026, The MITRE Corporation, used under the CAPEC terms of use: “The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use Common Attack Pattern Enumeration and Classification (CAPEC™) for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE’s copyright designation and this license in any such copy.” CAPEC and the CAPEC logo are trademarks of The MITRE Corporation. Credits. All attack patterns.