CVE-2018-3955

Home/CVE/An exploitable operating system command injection exists in the Linksys ESeries line of routers (Linksys E1200 Firmware

CVE

An exploitable operating system command injection exists in the Linksys ESeries line of routers (Linksys E1200 Firmware

An exploitable operating system command injection exists in the Linksys ESeries line of routers (Linksys E1200 Firmware Version 2.0.09 and Linksys E2500 Firmware Version 3.0.04). Specially crafted entries to network configuration information can cause execution of arbitrary system commands, resulting in full control of the device. An attacker can send an authenticated HTTP request to trigger this vulnerability.

Data entered into the 'Domain Name' input field through the web portal is submitted to apply.cgi as the value to the 'wan_domain' POST parameter. The wan_domain data goes through the nvram_set process described above. When the 'preinit' binary receives the SIGHUP signal it enters a code path that calls a function named 'set_host_domain_name' from its libshared.so shared object.

HIGH · CVSS 7.2 EPSS 0.01445

Act now

Public exploit or PoC is available
CVSS base score ≥ 7.0

Sigma rules0 YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA Vulners Exploit-DB GitHub PoC VulnCheck KEV GreyNoise

▸ How to read a CVE - triage first, then detect and patch

This page is every public fact about CVE-2018-3955, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.

Triage: should I act now? Four signals, and they are not interchangeable:

CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked. EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal. CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score. Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.

How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.

Then what - two workflows:

Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits. PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.

Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).

View attack path from CVE-2018-3955

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ATT&CK techniques

Techniques this CVE enables - linked via CWECAPECATT&CK. High◆ = named directly in ATT&CK or Nuclei templates.

T1078 · Valid Accounts

▤ Build a SIEM detection for these techniques

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CAPEC attack patterns

Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.

CAPEC-CAPEC-108 · Command Line Execution through SQL Injection CAPEC-CAPEC-15 · Command Delimiters CAPEC-CAPEC-43 · Exploiting Multiple Input Interpretation Layers CAPEC-CAPEC-6 · Argument Injection CAPEC-CAPEC-88 · OS Command Injection

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Weakness Classification

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

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Affected Products & Versions

linksys e1200 firmwareall versions

linksys e2500 firmwareall versions

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Public Exploits & PoCs

These PoC and exploit links come from public sources and are not verified to be safe or functional. Review the code before running anything, and treat unverified entries as untrusted.

pocPublic PoC (nvd-reference)

poctalosintelligence.com · TALOS-2018-0625talosintelligence.com

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Scoring & Timeline

7.2

HIGH · CVSS v3.1 · [email protected]

View on NVD

Attack Vector

Network Adjacent Local Physical

Attack Complexity

Low High

Privileges Required

None Low High

User Interaction

None Required

Scope

Unchanged Changed

Confidentiality

None Low High

Integrity

None Low High

Availability

None Low High

Published to NVD17 Oct 2018 · 02:29 AM

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H