WebWasher恶意脚本过滤器绕过漏洞

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漏洞ID 1196798 漏洞类型 设计错误
发布时间 2005-12-22 更新时间 2006-06-06
CVE编号 CVE-2005-4514 CNNVD-ID CNNVD-200512-518
漏洞平台 N/A CVSS评分 5.0
|漏洞来源
https://cxsecurity.com/issue/WLB-2005120071
http://www.cnnvd.org.cn/web/xxk/ldxqById.tag?CNNVD=CNNVD-200512-518
|漏洞详情
**争议**WebwasherCSMApplianceSuite5.x中的封装脚本机制使用大小写敏感的恶意令牌侦测,攻击者因此可以通过使用可大写或小写的令牌来绕过脚本侦测。
|漏洞EXP
Vendor: Webwasher (http://www.webwasher.com/)
Product: Webwasher CSM Appliance
Affected versions: CSM Suite 5.x
Author: .v0rt3x (d0tv0rt3x[at]gmail[d0t]com)
Date: 2005-Dec-22

....Background....
"...Webwasher appliances provide high-performance "Proactive
Filtering" of bidirectional SMTP, HTTP, HTTPS, and FTP traffic to
detect and cleanse all forms of malware. The result is a security
appliance that delivers the Blended Protection you need to protect
against malicious content and unwanted email..."

....Description....
Webwasher CSM includes an encapsulation script mechanism with the aim
of filtering malicious scripts.
The encapsulation script makes use of specific potentially malicious
tokens in order to detect and neutralize the malicious script.
The detection of the tokens is case sensitive. However, some of the
tokens can be executed whether they are written in lower case or upper
case letters.
In other words, by creating a specially crafted script, an attacker
can bypass the filtering mechanism and execute malicious scripts.

....Proof.of.Concept....
1) Create a malicious script by using an object which executes ".Run"
method (e.g. one of the many WScript.Shell exploits).
2) Replace ".Run" with ".run".
3) Execute the malicious script "safely" through Webwasher CSM.

....Timeline....
2005-May-15: Vendor was notified by mail.
2005-Aug-15: Vendor was notified again via contact form.
2005-Dec-22: No response from the vendor - public disclosure.


SecurityReason UPDATE :
--------------------------------------------------------------
The Proactive Security Filter is one of several security filters in the
Webwasher CSM Suite. It can block or mitigate many day zero threats
before their signature is added to the integrated Antivirus engines.
While we never claimed it can detect 100% of new malware, we are
continously improving the filter and welcome every input about new
attack vectors.

To respond to your posting:

1) First tests today do not confirm that (at least the current version
of the product) is vulnerable as described. We checked the code and ran
a few tests and confirmed that the handling is case in-sensitive. We'll
run more tests and also check older versions after the Christmas
holidays.

2) What we need from you is a proof of concept script that you think
should be mitigated by the Proactive Filter but is not. Please contact
me directly so we can work together to further improve our Proactive
Security Filter.

Btw, we have double-checked our records and found no evidence of being
contacted prior to this posting yesterday. We have attempted to contact
you, but got no response (so far). Also, we believe the timing of this
posting - a day before Christmas - is very bad and not intented to
giving us a fair chance to resolve this as quickly as we normally could.

Thanks, Frank
---------------------------------------------------------------
|参考资料

来源:BID
名称:16047
链接:http://www.securityfocus.com/bid/16047
来源:BUGTRAQ
名称:20060103RE:WebwasherCSMApplianceScriptSecurityRestrictionBypass
链接:http://www.securityfocus.com/archive/1/archive/1/420678/100/0/threaded
来源:BUGTRAQ
名称:20051223RE:WebwasherCSMApplianceScriptSecurityRestrictionBypass
链接:http://www.securityfocus.com/archive/1/archive/1/420158/100/0/threaded
来源:BUGTRAQ
名称:20051222WebwasherCSMApplianceScriptSecurityRestrictionBypass
链接:http://www.securityfocus.com/archive/1/archive/1/420106/100/0/threaded
来源:XF
名称:webwasher-security-bypass(23884)
链接:http://xforce.iss.net/xforce/xfdb/23884
来源:SREASON
名称:293
链接:http://securityreason.com/securityalert/293