Rule Category

PROTOCOL-TELNET -- Snort has detected traffic that may indicate the presence of the telnet protocol or vulnerabilities in the telnet protocol on the network.

Alert Message

PROTOCOL-TELNET FreeBSD telnetd enc_keyid overflow attempt

Rule Explanation

Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT Kerberos Version 5 Applications (aka krb5-appl) 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU inetutils, and possibly other products allows remote attackers to execute arbitrary code via a long encryption key, as exploited in the wild in December 2011. Impact: CVSS base score 10.0 CVSS impact score 10.0 CVSS exploitability score 10.0 confidentialityImpact COMPLETE integrityImpact COMPLETE availabilityImpact COMPLETE Details: Ease of Attack:

What To Look For

This rule detects specially crafted telent request packet that allows remote attackers to execute arbitrary code via a long encryption key.

Known Usage

No public information

False Positives

No known false positives

Contributors

Talos research team. This document was generated from data supplied by the national vulnerability database, a product of the national institute of standards and technology. For more information see [nvd].

MITRE ATT&CK Framework

Tactic: Initial Access

Technique: Exploit Public-Facing Application

For reference, see the MITRE ATT&CK vulnerability types here: https://attack.mitre.org

CVE

Additional Links

Rule Vulnerability

Buffer Overflow

Buffer Overflows occur when a memory location is filled past its expected boundaries. Computer attackers target systems without proper terminating conditions on buffers, which then write the additional information in other locations in memory, overwriting what is there. This could corrupt the data, making the system behave erratically or crash. The new information could include malicious executable code, which might be executed.

CVE Additional Information

CVE-2011-4862
Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT Kerberos Version 5 Applications (aka krb5-appl) 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU inetutils, and possibly other products allows remote attackers to execute arbitrary code via a long encryption key, as exploited in the wild in December 2011.
Details
SeverityHIGH Base Score10.0
Impact Score10.0 Exploit Score10.0
Confidentiality ImpactCOMPLETE Integrity ImpactCOMPLETE
Availability ImpactCOMPLETE Access Vector
AuthenticationNONE Ease of Access