Title: Symantec Client Firewall NetBIOS Name Service Response Buffer Overflow Vulnerability
Severity: CRITICAL
Description:
A vulnerability has been identified in Symantec Client Firewall products that may allow a remote attacker to execute arbitrary code on a vulnerable system. This issue could allow an attacker to gain unauthorized SYSTEM level access to a vulnerable host.
The issue presents itself due to insufficient boundary checks performed by the applications when processing NetBIOS Name Service responses that are of INET class (corresponding to 01h in the packet) with a type of either 'A' or 'NB' (corresponding to 01h and 20h respectively). Specifically, the issue exists in the 'SYMDNS.SYS' component of the firewall products.
When the firewall receives a packet of the previously mentioned type it will attempt to decode the name reported in the packet as well as the IP addresses. The name field contains a corresponding size field that is used to parse the string; this size field can specify a size of up to 127 bytes, while the buffer that stores the name string is a mere 32 bytes.
Although the above overflow is not sufficient to manipulate the instruction pointer stored on the stack, it is possible to manipulate an array index; the array index that is subsequently used in a loop to copy the IP addresses from the network message into a local buffer.
Reportedly the loop will only terminate when the target index equals the array size (18h); an index that is already greater than the array size will continue to loop, copying a maximum of 64 kilobytes into the finite buffer. With this it is possible to manipulate the instruction pointer stored on the stack and execute arbitrary code.
As a result, an attacker on a local network could send a malformed Name Service response that overflows a vulnerable buffer. If the attacker succeeds in over writing sensitive memory addresses, the flow of execution could be changed to point to attacker-supplied addresses containing arbitrary code.
A successful attack could allow an attacker to gain SYSTEM level privileges on a vulnerable system.
Affected Products:
- Symantec Client Firewall 5.0.01
- 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 0.0.0
- Symantec Norton Internet Security 2002 Professional Edition 0.0.0
- Symantec Norton Internet Security 2003 0.0.0
- Symantec Norton Internet Security 2003 Professional Edition 0.0.0
- Symantec Norton Internet Security 2004
- Symantec Norton Internet Security 2004 Professional Edition
- Symantec Norton Personal Firewall 2002 0.0.0
- Symantec Norton Personal Firewall 2003 0.0.0
- Symantec Norton Personal Firewall 2004 0.0.0
References:
- Symantec: SYM04-008 Symantec Client Firewall Remote Access and Denial of Service Issues
- eEye Digital Security: Symantec Multiple Firewall NBNS Response Processing Stack Overflow
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