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Malicious Ads from Yahoo Just the Tip of the Iceberg

TRACWhen Fox-IT published their report regarding malvertisements coming from Yahoo, they estimated the attack began on December 30, 2013, while also noting that other reports indicated the attack may have begun earlier. Meanwhile, Yahoo intimated a different timeframe for the attack, claiming “From December 31 to January 3 on our European sites, we served some advertisements that did not meet our editorial guidelines – specifically, they spread malware.”

With so much uncertainty regarding this attack, Cisco TRAC decided to review what data we had to see if we could sort out some of the competing claims. Cisco Security Intelligence Operations data regarding the Yahoo incident supports the conclusion that the attack against Yahoo began on December 31. However, the malicious advertisements were just one attack in a long series of other attacks waged by the same group.

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The Internet of Everything, Including Malware

December 4, 2013 at 1:09 pm PST

We are witnessing the growth of the Internet of Everything (IoE), the network of embedded physical objects accessed through the Internet, and it’s connecting new devices to the Internet which may not traditionally have been there before. Unfortunately, some of these devices may be deployed with a security posture that may need improvement.

Naturally when we saw a few posts about multi-architecture malware focused on the “Internet of Things”, we decided to take a look. The issue being exploited in those posts is CVE-2012-1823, which has both an existing Cisco IPS signature as well as some for Snort. It turns out this vulnerability is actually quite heavily exploited by many different worms, and it took quite a bit of effort to exclude all of the alerts generated by other pieces of malware in Cisco IPS network participation. Due to the vulnerability-specific nature of the Cisco IPS signature, the same signature covers this issue as well as any others that use this technique; just one signature provides protection against all attempts to exploit this vulnerability.  As you can see in the graph below this is a heavily exploited vulnerability. Note that these events are any attack attempting to exploit this issue, not necessarily just the Zollard worm.

The graph below is derived from both Cisco IPS and Sourcefire IPS customers. The Cisco data is from customers who have ‘opted-in’ to network participation. This service is not on by default. The Sourcefire data below is derived from their SPARK network of test sensors. This graph is showing the percent increase of alert volume from the normal for each dataset at the specified time.

zollard_cisco_sf

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Don’t Click Tired

As the day draws to a close, and especially during the early morning, users become far more likely to click on links that lead to malware. Those responsible for network security need to ensure that users’ awareness of information security continues after work hours, so that users “don’t click tired.”
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New Fake UPS Malware Email Campaign

We have detected evidence of a malware distribution campaign using messages masquerading as UPS delivery notification emails. These campaigns attempt to deceive the targets into thinking they are receiving mail from a trusted sender in order to dupe the recipient into installing malware, possibly for financial gain. Once the initial attack vector is installed, further malware may be distributed.

This  appears to be part of the same campaign seen by MalwareMustDie (http://pastebin.com/n244xN32) and uses the email subject “UPS Delivery Notification Tracking Number”. We have seen a limited number of customers receiving this spam starting yesterday (Tue Nov 5), suggesting that this is a fairly low volume campaign (at the moment). The message contains an attachment with a filename such as “invoiceU6GCMXGLL2O0N7QYDZ” and extension .txt or .doc which is a disguised rtf file.

Section of the mail attachment containing rtf objocx tag

Section of the mail attachment containing rtf objocx tag

According to our analysis the malware attempts to download additional files by exploiting CVE-2012-0158 affecting old versions of Microsoft Office, which is detected by Cisco IPS signature 1131 and is available as a Metasploit module. In this case the malware being distributed seems to be a form of ransomware. Ransomware typically encrypts files on an infected machine and requires the user to pay for the release of their data. This particular piece of ransomware appears to be distinct from the samples we have been seeing as part of the Cryptolocker campaign, but comes in the wake of increased interest and discussion of this kind of attack.

    Attached malware making a request to the control server at 199.16.199.2

Attached malware making a request to the control server at 199.16.199.2

As ever, users should remain vigilant when opening email links and attachments, and be wary of a message purporting to be an automated order confirmation from a company such as FedEx and UPS, as this is a common tactic which has also been identified as a possible method for distributing Cryptolocker.

Additional analysis of this attack can be found here: http://bartblaze.blogspot.com/2013/11/latest-ups-spam-runs-include-exploits.html

Malicious rtf:   7c2fd4abfe8640f8db0d18dbecaf8bb4

Downloaded exe:     e5e1ee559dcad00b6f3da78c68249120

 

Thanks to Cisco researchers Craig Williams and Martin Lee for assistance with this post.

 

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DNS Knows. So Why Not Ask?

DNS is like the town gossip of the network infrastructure. Computers and apps ask DNS questions and you can ask DNS who has been asking to resolve malware domains. When internal trusted systems are using DNS to resolve the names of known malware sites, this can be an Indicator of Compromise and a warning to clean the potentially infected systems and block traffic to the domain.

Blacklisting the known malware domains using local RPZs, firewalls, Cisco IronPort Web Security Appliance (WSA), or Cloud Web Security (CWS) is a great way to add an extra level of security in organizations. But what if you are just getting started in the process of cleaning systems and just need some situational awareness? Or, how can you manually check to see if these devices are working as expected? How can you determine independently of security devices, and at any point in time, that client systems are not reaching out to malicious domains? You can use dig but this post focuses on a Python example. Let’s first take a look at some DNS mechanics.

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