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Zhone Vulnerability

Zhone ADSL2+ 4P Bridge & Router (Broadcom)

References (Source): http://www.vulnerability-lab.com/get_content.php?id=1591

Download: http://www.zhone.com/support/downloads/cpe/6218-I2/6218-I2_R030220_AnnexA.zip

Release Date: 2015-09-03

Vulnerability Laboratory ID (VL-ID): 1591

Common Vulnerability Scoring System: 8.8

Product & Service

At Zhone, Bandwidth Changes Everything™ is more than just a tag line. It is our focus, our fundamental belief and philosophy in developing carrier and enterprise-grade fiber access solutions for our customers ensuring bandwidth is never a constraint in the future!

(Copy of the Vendor Homepage: http://www.zhone.com/support/ )

Abstract Advisory Information

2015-09-03: Public Disclosure (Vulnerability Laboratory)

Discovery Status: Published

Affected Product(s): Product: Zhone ADSL2+ 4 Port Bridge (Broadcom) & Zhone ADSL2+ 4 Port Router (Broadcom) 6218-I2-xxx - FW: 03.02.20

Exploitation Technique: Remote

Severity Level: High

Technical Details

An authentication bypass vulnerability has been discovered in the official in the official Zhone ADSL2+ 4 Port Wireless Bridge & Router (Broadcom). The vulnerability allows remote attackers to bypass the authentication procedure to compromise the hardware device or service interface.

The first vulnerability is located in the session validation when processing to request via GET (outside the network) the pvccfg.cgi,dnscfg.cgi and password.cgi files. Thus can results in a reconfiguration by the attacker to compromise the hardware device.

The second vulnerability is located in the backupsettings.conf file access rights. Remote attackers can easily request via curl the backupsettings of the hardware device. Thus can result in an easy take-over of the hardware device via an information disclosure by accessing the backupsettings.conf.

The security risk of both vulnerabilities are estimated as high with a cvss (common vulnerability scoring system) count of 8.8. Exploitation of the access privilege issue requires no privilege application user account or user interaction. Successful exploitation of the bug results in hardware device compromise.

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Request Method(s):
[+] GET

Vulnerable Model(s):
[+] Zhone ADSL2+ 4 Port Bridge (Broadcom)
[+] Zhone ADSL2+ 4 Port Router (Broadcom)

Affected Firmware:
[+] 03.02.20

Product Name:
[+] 6218-I2-xxx

Proof of Concept

The vulnerabilities can be exploited by remote attackers without privilege device user account or user interaction. For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.

PoC: #1

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http://[LOCALHOST]:?/pvccfg.cgi
http://[LOCALHOST]:?/dnscfg.cgi
http://[LOCALHOST]:?/password.cgi (In addition to text storage of sensitive information!)

Note: The links above can be accessed without any authentication in the interface!

PoC: #2

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curl "http://<IP>/backupsettings.conf" -H "Authorization: Basic dXNlcjp1c2Vy"

("dXNlcjp1c2Vy" = "user:user" in base64)

Note: Obtaining backup DSL router configurations by any users account authentication!

Security Risk

The security risk of the both vulnerabilities in the bridge and wireless router interface is estimated as high. (CVSS 8.8)