VU#876780: D-Link DSL2730U router restricted telnet shell command whitelisting bypass

Vulnerability Note VU#876780
D-Link DSL2730U router restricted telnet shell command whitelisting bypass

Original Release date: 12 Dec 2012 | Last revised: 12 Dec 2012

Overview

D-Link DSL2730U routers contain a restricted telnet shell with limited allowed commands. An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Description

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

D-Link DSL2730U routers contain a restricted telnet shell with limited allowed commands. Commands entered in the restricted telnet shell are executed by passing them as command parameters of execution “sh -c”, for example, “echo | ls” will result in passing a whitelisted command (echo) and executing “sh -c echo | ls” on the underlying Linux environment. The STDOUT output of the command execution is returned to the telnet terminal. An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Impact

An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Solution

We are currently unaware of a practical solution to this problem.

Restrict Access

As a general good security practice, only allow connections from trusted hosts and networks. Restricting access would prevent an attacker from accessing an telnet interface using the affected credentials from a blocked network location.

Vendor Information (Learn More)

VendorStatusDate NotifiedDate UpdatedD-Link Systems, Inc.Affected01 Nov 201203 Dec 2012If you are a vendor and your product is affected, let
us know.

CVSS Metrics (Learn More)

Group
Score
Vector

Base
6.8
AV:N/AC:L/Au:S/C:C/I:N/A:N

Temporal
5.2
E:POC/RL:W/RC:UC

Environmental
1.4
CDP:L/TD:L/CR:ND/IR:ND/AR:ND

References

http://cwe.mitre.org/data/definitions/78.html

Credit

Thanks to Nikolay Dachev for reporting this vulnerability.

This document was written by Michael Orlando.

Other Information

CVE IDs:
CVE-2012-5966

Date Public:
12 Dec 2012

Date First Published:
12 Dec 2012

Date Last Updated:
12 Dec 2012

Document Revision:
7

Feedback

If you have feedback, comments, or additional information about this vulnerability, please send us email.

“security” via n8xja in Google Reader 2012-12-12 06:35:26

Vulnerability Note VU#876780
D-Link DSL2730U router restricted telnet shell command whitelisting bypass

Original Release date: 12 Dec 2012 | Last revised: 12 Dec 2012

Overview

D-Link DSL2730U routers contain a restricted telnet shell with limited allowed commands. An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Description

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

D-Link DSL2730U routers contain a restricted telnet shell with limited allowed commands. Commands entered in the restricted telnet shell are executed by passing them as command parameters of execution “sh -c”, for example, “echo | ls” will result in passing a whitelisted command (echo) and executing “sh -c echo | ls” on the underlying Linux environment. The STDOUT output of the command execution is returned to the telnet terminal. An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Impact

An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Solution

We are currently unaware of a practical solution to this problem.

Restrict Access
As a general good security practice, only allow connections from trusted hosts and networks. Restricting access would prevent an attacker from accessing an telnet interface using the affected credentials from a blocked network location.

Vendor Information (Learn More)
VendorStatusDate NotifiedDate UpdatedD-Link Systems, Inc.Affected01 Nov 201203 Dec 2012If you are a vendor and your product is affected, let
us know.
CVSS Metrics (Learn More)
Group
Score
Vector
Base
6.8
AV:N/AC:L/Au:S/C:C/I:N/A:N
Temporal
5.2
E:POC/RL:W/RC:UC
Environmental
1.4
CDP:L/TD:L/CR:ND/IR:ND/AR:ND
References
http://cwe.mitre.org/data/definitions/78.html
Credit

Thanks to Nikolay Dachev for reporting this vulnerability.

This document was written by Michael Orlando.

Other Information
CVE IDs:
CVE-2012-5966
Date Public:
12 Dec 2012
Date First Published:
12 Dec 2012
Date Last Updated:
12 Dec 2012
Document Revision:
7
Feedback

If you have feedback, comments, or additional information about this vulnerability, please send us email.

“security” via n8xja in Google Reader 2012-12-12 06:35:26

Vulnerability Note VU#876780
D-Link DSL2730U router restricted telnet shell command whitelisting bypass

Original Release date: 12 Dec 2012 | Last revised: 12 Dec 2012

Overview

D-Link DSL2730U routers contain a restricted telnet shell with limited allowed commands. An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Description

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

D-Link DSL2730U routers contain a restricted telnet shell with limited allowed commands. Commands entered in the restricted telnet shell are executed by passing them as command parameters of execution “sh -c”, for example, “echo | ls” will result in passing a whitelisted command (echo) and executing “sh -c echo | ls” on the underlying Linux environment. The STDOUT output of the command execution is returned to the telnet terminal. An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Impact

An authenticated attacker can chain unauthorized commands through authorized commands in order to bypass the command whitelisting.

Solution

We are currently unaware of a practical solution to this problem.

Restrict Access
As a general good security practice, only allow connections from trusted hosts and networks. Restricting access would prevent an attacker from accessing an telnet interface using the affected credentials from a blocked network location.

Vendor Information (Learn More)
VendorStatusDate NotifiedDate UpdatedD-Link Systems, Inc.Affected01 Nov 201203 Dec 2012If you are a vendor and your product is affected, let
us know.
CVSS Metrics (Learn More)
Group
Score
Vector
Base
6.8
AV:N/AC:L/Au:S/C:C/I:N/A:N
Temporal
5.2
E:POC/RL:W/RC:UC
Environmental
1.4
CDP:L/TD:L/CR:ND/IR:ND/AR:ND
References
http://cwe.mitre.org/data/definitions/78.html
Credit

Thanks to Nikolay Dachev for reporting this vulnerability.

This document was written by Michael Orlando.

Other Information
CVE IDs:
CVE-2012-5966
Date Public:
12 Dec 2012
Date First Published:
12 Dec 2012
Date Last Updated:
12 Dec 2012
Document Revision:
7
Feedback

If you have feedback, comments, or additional information about this vulnerability, please send us email.

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