Title: Symantec Client Firewall DNS Response Buffer Overflow Vulnerability
Severity: CRITICAL
Description:
A remotely exploitable buffer overflow vulnerability has been reported in various Symantec Firewall Products. Affected products include Norton Internet Security, Norton Personal Firewall, Norton AntiSpam, Client Firewall, and Client Security.
The issue is due to insufficient bounds checking of DNS response data. The vulnerable function exists in the SYMDNS.SYS file. In particular, malicious DNS response data may trigger memory corruption in the client process, potentially influencing execution flow in the affected process.
The source of the vulnerability is that the CNAME (Canonical Name) data field specified in incoming DNS Resource Records is copied into an internal buffer in an insecure manner, resulting in a stack-based buffer overflow. Specifically, an excessive number of malicious length specifiers and byte sequences within the CNAME data may cause attacker-supplied data to be concatenated past the end of the declared destination buffer.
It should be noted that there is an additional design flaw in the software that will aid in exploitation. Reportedly, the firewall will accept inbound traffic that specifies a source port of 53, regardless of any access controls or port filtering rules that have been enabled in the software. As a result, this issue may be exploited with a spoofed UDP packet and does not require the client to initiate a DNS query prior to the malicious response packet.
This issue may be exploited to execute code with SYSTEM/kernel level privileges on a computer hosting the vulnerable software.
Affected Products:
- Symantec Client Firewall 5.0.0 1
- Symantec Client Firewall 5.1.1
- Symantec Client Security 1.0.0
- Symantec Client Security 1.1.0
- Symantec Client Security 2.0.0 (SCF 7.1)
- Symantec Norton AntiSpam 2004
- Symantec Norton Internet Security 2002
- Symantec Norton Internet Security 2002 Professional Edition
- Symantec Norton Internet Security 2003
- Symantec Norton Internet Security 2003 Professional Edition
- Symantec Norton Internet Security 2004
- Symantec Norton Internet Security 2004 Professional Edition
- Symantec Norton Personal Firewall 2002
- Symantec Norton Personal Firewall 2003
- Symantec Norton Personal Firewall 2004
References:
- CERT: Vulnerability Note VU#294998 - Multiple Symantec firewall
- CERT: Vulnerability Note VU#637318 - Multiple Symantec firewall
- Symantec: SYM04-008 Symantec Client Firewall Remote Access and Denial of Service Issues
- eEye Digital Security: Symantec Multiple Firewall Remote DNS KERNEL Overflow
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