Category: sans internet storm center

Oct 11 2017

Krebs on Security 2017-10-11 10:18:40

Microsoft on Tuesday released software updates to fix at least 62 security vulnerabilities in Windows, Office and other software. Two of those flaws were detailed publicly before yesterday’s patches were released, and one of them is already being exploited in active attacks, so attackers already have a head start.

brokenwindowsRoughly half of the flaws Microsoft addressed this week are in the code that makes up various versions of Windows, and 28 of them were labeled “critical” — meaning malware or malicious attackers could use the weaknesses to break into Windows computers remotely with no help from users.

One of the publicly disclosed Windows flaws (CVE-2017-8703) fixed in this batch is a problem with a feature only present in Windows 10 known as the Windows Subsystem for Linux, which allows Windows 10 users to run unmodified Linux binary files. Researchers at CheckPoint recently released some interesting research worth reading about how attackers might soon use this capability to bypass antivirus and other security solutions on Windows.

The bug quashed this week that’s being actively exploited resides in Microsoft Office (CVE-2017-11826), and Redmond says attackers could seize control over a vulnerable system just by convincing someone to open a booby-trapped Word file. Another Office vulnerability, (CVE-2017-11776), involves a flaw in Outlook’s ability to encrypt messages; SEC-Consult has more details on this bug.

Another critical flaw (CVE-2017-11779) addresses a scary vulnerability in the domain name system (DNS) component of Windows 8 and Windows Server 2012. According to research from Bishop Fox, the security firm credited with finding and reporting the bug, this flaw could be exploited quite easily to gain complete control over vulnerable systems if the attacker controls or compromises a local network (think Wi-Fi hotspot).

Normally, Adobe uses Microsoft’s Patch Tuesday (the second Tuesday of each month) to release its own fixes for Flash Player, Reader and other products. However, this time around the company has no security updates available. Adobe did release a new version of Flash that includes bug fixes (v. 27.0.0.159), but generally speaking only even-numbered Flash releases include security fixes.

For additional commentary on October’s bundle of updates from Microsoft, see these blogs from security vendors Ivanti and Qualys. For those looking for a straight-up list of which patches deserve priority, check out the always useful roundup from the SANS Internet Storm Center.

Mar 13 2014

Blogs of War: Don’t Be Cannon Fodder

On Wednesday, KrebsOnSecurity was hit with a fairly large attack which leveraged a feature in more than 42,000 blogs running the popular WordPress content management system (this blog runs on WordPress). This post is an effort to spread the word to other WordPress users to ensure their blogs aren’t used in attacks going forward.

armyAt issue is the “pingback” function, a feature built into WordPress and plenty of other CMS tools that is designed to notify (or ping) a site that you linked to their content. Unfortunately, like most things useful on the Web, the parasites and lowlifes of the world are turning pingbacks into a feature to be disabled, lest it be used to attack others.

And that is exactly what’s going on. Earlier this week, Web site security firm Sucuri Security warned that it has seen attackers abusing the pingback function built into more than 160,000 WordPress blogs to launch crippling attacks against other sites.

“Any WordPress site with Pingback enabled (which is on by default) can be used in DDOS attacks against other sites,” Sucuri’s Daniel Cid wrote. “One attacker can use thousands of popular and clean WordPress sites to perform their DDOS attack, while being hidden in the shadows, and that all happens with a simple ping back request.”

Bloggers can disable pingback on posts by clicking “Settings” then “Discussion”, and then unchecking the following options if they are checked:

-Attempt to notify any blogs linked to from the article
-Allow link notifications from other blogs (pingbacks and trackbacks)

Unfortunately, Cid said, this only appears to prevent pingbacks on new blog posts and does nothing to disable pingbacks on posts that are already published for which pingback was previously enabled. There is, however, a highly-rated WordPress plugin that disables the pingback functionality.

As Sucuri notes, for the gearheads who don’t trust plugins, one easy way to block your WordPress blog from participating in these attacks is to create your own plugin that incorporates the following code:

add_filter( ‘xmlrpc_methods’, function( $methods ) {
unset( $methods['pingback.ping'] );
return $methods;
} );

Sucuri has declined to release the list of WordPress sites that are being used in these attacks, but it has posted an online tool that blog administrators can use to learn if their blogs have shown up in attack logs.

My hosting provider shared with me a list of the WordPress blogs that were used in the attack on this blog. I’m sharing it here to get the attention of WordPress administrators. I realize that some readers will view this as providing a roadmap for attacks, but I’m hopeful that making this information public will decrease the number of blogs that can be used in future such attacks.

The guys over at OpenDNS have more raw data on these attacks in a blog post that’s worth a read.