Internet Explorer, Sendmail and RealPlayer are the packages with critical vulnerabilities discovered this week.
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).
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Part I is compiled by Rohit Dhamankar at TippingPoint, a division of 3Com, 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: Internet Explorer contains a heap memory corruption vulnerability that can be triggered by a JavaScript call to "createTextRange" method. This method is used to create "textRange" object that represents text in an HTML element. Invoking the "createTextRange" method on a "checkbox" object can be exploited to corrupt heap memory that leads to arbitrary code execution. A specially crafted webpage or an HTML email can exploit this flaw to compromise a user's system. Exploit code has been publicly posted and attacks have been recorded in the wild. SANS Internet Storm Center reports that around 100 sites using the exploit to install Trojans and other malware on compromised systems. A researcher has posted a tool that can be used to stress test the implementation of other DHTML methods, and reported that Internet Explorer crashes on three other instances. Another researcher has reportedly found a flaw in IE that can be used to run arbitrary HTA code.
Status: Microsoft is aware of the issues and is working on releasing the fix along with the April patches. Microsoft is also planning to roll changes in IE's automatic handling of multimedia content in the next patch that may cause issues with certain websites (EOLAS changes). A workaround is to turn off the "Active Scripting" option in IE (which will break normal functioning of many webpages) or use another browser like Firefox. Use updated AV and IDS/IPS signatures to prevent users from loading malicious webpages or emails. Council Site Actions: Most are reviewing turning off "Active Scripting", but will likely wait for vendor patch/fix. The great majority will obtain the update through the public Microsoft Update site, or through their local WSUS server, whenever Microsoft releases a patch. Antivirus may buy some degree of protection in the meantime.
Description: Sendmail is the most common mail transfer agent (MTA) used on the Internet and according to certain estimates handles between 50 and 75% of the e-mail traffic. Sendmail contains a vulnerability in its "signal" handling code that deals with "timeouts" during SMTP connections. (Signals are used to communicate to a process or a thread about certain events.) A remote attacker can trigger the vulnerability by sending a sequence of SMTP commands with certain timing conditions along with a specially crafted e-mail message. The flaw can be exploited to corrupt the process stack or heap memory, and execute arbitrary code with the privileges of sendmail process (root in older versions). Proof-of-concept exploit has been publicly posted.
Status: Sendmail has released version 8.13.6 to fix the problem. Patches for versions 8.15.5 and 8.12.11 are also available. Major Linux vendors like RedHat, Gentoo, OpenPKG, Fedora have released updated sendmail packages. Sun and IBM have also released patches for Solaris and AIX respectively. For other affected vendors, please refer to the CERT advisory.
Council Site Actions: One site has sendmail enabled only to listen on loopback only mode and they plan to deploy the patch during their next regularly scheduled system maintenance cycle. Another site is affected only on its Sun platforms and they are currently testing the patches and will deploy soon. The third site plans to deploy patches for heavily used systems after some initial testing over the next few weeks. Their lightly used system will automatically obtain updates from their Linux distributors.
Description: RealPlayer contains multiple vulnerabilities that can lead to remote compromise of users' systems running the vulnerable version of the media players. (a) The players contain a buffer overflow in handling specially crafted SWF and MBC file formats. A malicious media file posted on a webpage, P2P or shared folder can exploit the overflows to execute arbitrary code on a client system. The technical details required to craft an exploit have not been released yet. (b) The players contain a heap-based overflow that can be triggered by specially crafted "chunked data" during HTTP download. Chunk transfer mechanism allows an HTTP server to break the data into smaller pieces or "chunks", and each chunk of data is preceded by its length. The heap corruption can be triggered by chunk with size -1 or chunk with data size greater than the declared length. A malicious server hosting a media file can exploit this overflow to execute arbitrary code on a client system.
Status: RealPlayer has issued fixed version for all the affected media players. Enable the "Autoupdate" feature available on the players to keep them updated.
Council Site Actions: The software is not officially supported at the reporting council sites, although it is used by many at the respective sites. Two sites are relying on the "Autoupdate" feature to download the latest version. The third site uses SMS to search for and remove the software from their workstations on a regular basis. This forces their user community to download and install the latest releases when they want to use the software.
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 4949 unique vulnerabilities. For this special SANS community listing, Qualys also includes vulnerabilities that cannot be scanned remotely.
(c) 2006. 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.
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