A quiet week for vulnerability remediation, but that makes it a great time to plan for some end-of-year, award-winning security training in Washington in December. More information at http://www.sans.org/cdieast04
Alan
@RISK is the SANS community's consensus bulletin summarizing the most important vulnerabilities and exploits identified during the past week and providing guidance on appropriate actions to protect your systems (PART I). It also includes a comprehensive list of all new vulnerabilities discovered in the past week (PART II).
********************* This Issue Sponsored by Radware *******************
Radware Intrusion Prevention Switch protects against worms, viruses, malicious intrusions, Denial of Service attacks and Trojans - securing networked applications at 3-Gbps. Featuring inline security switching and accelerated, stateful and deep-packet inspection, DefensePro isolates attacks and dynamically moderates bandwidth to stop propagation across the network. http://www.radware.com/content/products/dp/whtpaper/_download-20040204b/form.asp
*************************************************************************
************************** SPONSORED LINKS ******************************
Privacy notice: Sponsored links redirect to non-SANS web pages.
(1) Simple, secure alternative to NIS/NIS+ and LDAP for UNIX/Linux user account and password management. FREE downloads. http://www.sans.org/info.php?id=649
(2) Employee Security Awareness? Solved! Find out how at http://www.sans.org/info.php?id=650
*************************************************************************
Highlighted Cybersecurity Training: Washington, DC, Dec. 7-13, 2004
SANS best instructors will be in DC teaching great courses for
*************************************************************************
Part I is compiled by the security team at TippingPoint (www.tippingpoint.com) as a by-product of that company's continuous effort to ensure that its intrusion prevention products effectively block exploits using known vulnerabilities. TippingPoint's analysis is complemented by input from a council of security managers from twelve large organizations who confidentially share with SANS the specific actions they have taken to protect their systems. A detailed description of the process may be found at http://www.sans.org/newsletters/cva/#process
Description: Cisco IOS contains a denial of service vulnerability thatcan be triggered by a series of specially crafted DHCP packets. The DHCPpackets may be directed to any of the router's interface IP addresses.A successful attack will cause the router to stop processing traffic onthe targeted interface(s). Further, after a period of 4 hours, therouter may be unable to route any traffic as the router's ARP cache willbe cleared. The problem arises because the crafted DHCP packets remainin the router's "input" queue, and the router stops processing trafficon any interface when the input queue gets full. A hard reboot isrequired to bring the router back to normalcy. Note that Cisco routersprocess DHCP packets by default. No technical details regarding how tocraft the packets that will trigger this vulnerability have been posted.
Status: Cisco has released corrected versions of IOS. A workaround isto configure "no service DHCP" on the routers that do not require DHCPservice.
Council Site Actions: Three of the reporting council sites are using theaffected software and version. One site has already applied the patch.The second site has disabled the DHCP service and does not pass DHCPthrough its firewalls. The third site will deploy the patch during itsnext regularly scheduled system update process.
Description: ISD DHCP software ships with almost all flavors of Linux.The DHCP server contains a format string vulnerability that can betriggered by a specially crafted DNS response. An attacker in controlof a DNS server on the same network as the DHCP server may exploit thisflaw to possibly execute arbitrary code on the DHCP server with rootprivileges. An attacker on the local network as the DHCP server may alsospoof a DNS response to exploit the flaw. Limited technical detailsregarding the flaw have been posted.
Status: Debian, which includes ISC DHCP versions 2.x in the stablerelease, has issued fixes. The version 2.x of DHCP is no longersupported by ISC. Please upgrade to stable 3.x version.
Council Site Actions: One council site responded and is stillinvestigating needed action. They use Lucent's QDDNS for DNS and DHCP,which bundles ISC DHCP. They believe that the Lucent software stilluses ISC version 2.x. However, the vulnerability seems to work only ifa hacker is able take over the local DNS server. Thus, they feel thereis no increased risk.
Description: The Microsoft ISA server and Proxy server are typicallydeployed between the intranet and the Internet, and are designed tocache Internet content to serve the intranet users. The servers containa vulnerability that can be exploited to spoof a malicious site suchthat it appears to be a trusted site. Hence, the vulnerability can beexploited to conduct phishing attacks to steal sensitive userinformation such as bank accounts. In order to exploit the flaw, anattacker has to host a malicious webserver and a DNS server. Theattacker has to entice an intranet user to visit this webserver via alink (in an email or webpage) that contains the IP address of theattacker's webserver. When the intranet user clicks such a link, the ISAor Proxy server automatically perform a reverse DNS look-up (a querythat correlates IP address with domain names) for the attacker'swebserver IP address. The attacker's DNS server can then provide anon-authoritative answer to the ISA or Proxy server's reverse DNS query,and claim that the attacker's IP address belongs to a trusted domainsuch as "citibank.com". The ISA or Proxy server caches the results ofthe reverse look-up. When the intranet user then tries to visit"citibank.com", he is directed to the attacker's webserver.
Status: Microsoft confirmed, apply the patch referenced in the MicrosoftSecurity Bulletin MS04-039.
Council Site Actions: Two of the reporting council sites are running theaffected software on a small number of systems. Both sites have deployedthe patch.
Description: This vulnerability in Internet Explorer allows an attackerto construct a malicious hyperlink that appears to point to a trustedsite, but in fact points to the attacker's site (phishing attack). Theflaw can be exploited to steal sensitive user information. These attacksare on a rise, and hundreds are being reported every week( http://www.antiphishing.org). The problem arises when an "object"element is embedded inside a hyperlink. IE's status bar shows thewebpage pointed by the hyperlink; however, when a user clicks such alink the webpage pointed by the embedded object's attribute is loaded.Proof of concept examples include embedding an Excel sheet or flashmovie in a hyperlink.
Status: Microsoft has not confirmed the vulnerability and has providedno patches.
Council Site Actions: All reporting council sites are waiting onconfirmation from Microsoft along with a patch.
Description: Multiple Mydoom a.k.a Bofra viruses are exploiting theInternet Explorer FRAME/IFRAME/EMBED tags' processing overflow discussedin the previous @RISK newsletters. The viruses send an email containinga link to a malicious webpage. When users click the link, the webpageexploits the flaw to compromise the users' systems. Since the maliciousweb servers are running on ports 1638/tcp, 1639/tcp, 1640/tcp etc. apossible workaround is to block HTTP requests to these ports.
Council Site Actions: All council sites are waiting on a patch fromMicrosoft. One site reported it is in the middle of a mid-size virusattack. Its mail servers have been set up to block emails fromcompromised machines as a temporary measure and it is disabling netaccess to infected systems.
Description: CCProxy proxy server is designed for small businesses toenable multiple computers to connect to the Internet via single Internetconnection. The proxy server can be configured as a web proxy, SOCKSproxy, IRC proxy etc. The server reportedly contains a stack-basedbuffer overflow that can be triggered by an overlong HTTP "GET" request.The overflow can be exploited to execute arbitrary code on the server.Exploit code has been publicly posted.
Status: Upgrade to version 6.2 to fix the flaw.Council Site Actions:The affected software is not in production or widespread use at any ofthe council sites. They reported that no action was necessary.
Description: SlimFTPd, a FTP server for Windows based platforms,contains multiple buffer overflow vulnerabilities. The flaws can betriggered by passing an overlong to multiple FTP commands such as CWD,MKD, STAT, STOR etc. The flaws can be exploited by an authenticatedattacker to execute arbitrary code on the server. Exploit code has beenposted. The FTP servers configured for anonymous access face the maximumrisk.
Status: Vendor confirmed, upgrade to version 3.16.Council Site Actions:The affected software is not in production or widespread use at any ofthe council sites. They reported that no action was necessary.
Description: IBM has acknowledged the MIT Kerberos vulnerabilities inits Tivoli Access Manager for e-business product.Council Site Actions:The affected software is not in production or widespread use at any ofthe council sites. They reported that no action was necessary.
This list is compiled by Qualys ( www.qualys.com ) as part of that company's ongoing effort to ensure its vulnerability management web service tests for all known vulnerabilities that can be scanned. As of this week Qualys scans for 3857 unique vulnerabilities. For this special SANS community listing, Qualys also includes vulnerabilities that cannot be scanned remotely.
(c) 2004. All rights reserved. The information contained in this newsletter, including any external links, is provided "AS IS," with no express or implied warranty, for informational purposes only. In some cases, copyright for material in this newsletter may be held by a party other than Qualys (as indicated herein) and permission to use such material must be requested from the copyright owner.
==end==
Subscriptions: @RISK is distributed free of charge to people responsible for managing and securing information systems and networks. You may forward this newsletter to others with such responsibility inside or outside your organization.
To subscribe, at no cost, go to https://portal.sans.org where you may also request subscriptions to any of SANS other free newsletters.
To change your subscription, address, or other information, visit http://portal.sans.org
Copyright 2004. All rights reserved. No posting or reuse allowed, other that listed above, without prior written permission.