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Threat Spotlight: A String of ‘Paerls’, Part One

June 30, 2014 at 7:00 am PST

This post was co-authored by Jaeson SchultzJoel Esler, and Richard Harman

Update 7-8-14: Part 2 can be found hereVRT / TRAC

This is part one in a two-part series due to the sheer amount of data we found on this threat and threat actor. This particular attack was a combined spearphishing and exploit attempt. As we’ve seen in the past, this can be a very effective combination.

In this specific example the attackers targeted a feature within Microsoft Word — Visual Basic Scripting for Applications. While basic, the Office Macro attack vector is obviously still working quite effectively.  When the victim opens the Word document, an On-Open macro fires, which results in downloading an executable and launching it on the victim’s machine. This threat actor has particularly lavish tastes.  This threat actor seem to target high-profile, money-rich industries such as banking, oil, television, and jewelry.

Discovering the threat

The VRT has hundreds of feeds of raw threat intelligence, ranging from suspicious URLs, files, hashes, etc.  We take that intelligence data and apply  selection logic to it to identify samples that are worthy of review.  Using various methods from machine learning to dynamic sandbox analysis, we gather details about the samples -- producing indicator of  compromise (IOC), and alerts made up of multiple IOCs.

During our analysis we took the last 45 days’ worth of samples, and clustered them together based on a matching set of alert criteria.  This process reduced over a million detailed sample reports to just over 15 thousand sample clusters that exhibit similar behavior.  Using this pattern of similar behavior, we were capable of identifying families of malware.  This led us to discover a Microsoft Word document that downloaded and executed a secondary sample, which began beaconing to a command and control server.

The Malicious Word documents & Associated Phishing campaign

The attacks we uncovered are an extremely targeted spear phish in the form of an invoice, purchase order, or receipt, written specifically for the recipient.  For instance, the following is an example message we observed that purportedly came from “Maesrk”, the shipping company.


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A Collection of Cryptographic Vulnerabilities.

TRAC logo
The rustic origins of the English language are evident in the words left to us by our agricultural ancestors. Many words developed to distinguish groups of different animals, presumably to indicate their relevant importance. A ‘flock’ of sheep was more valuable than a single sheep, a ‘pack’ of wolves posed more danger than a single wolf. With respect to security vulnerabilities, we have yet to develop such collective nouns to indicate what is important, and to indicate that which poses danger.

The world of Transport Layer Security has been rattled once again with the identification of a “swarm” of vulnerabilities in OpenSSL and GnuTLS. A total of seven new vulnerabilities ranging from a potential man in the middle attack, allowing an attacker to eavesdrop on an encrypted conversation, to vulnerabilities that could be used to allow attackers to remotely exploit code on a client have been identified in the popular open source libraries.
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RIG Exploit Kit Strikes Oil

This post was co-authored by Levi Gundert with contributions from Emmanuel Tacheau and Joel Esler.

In the last month we have observed high levels of traffic consistent with the new “RIG” exploit kit (EK), as identified by Kahu Security. This new EK reportedly began being advertised on criminal forums in April, which coincides with when we first began blocking this traffic on April 24th. Whilst the release of a new EK is not uncommon, RIG’s appearance is significant in three ways. First, because of the sheer amount of traffic we are seeing -- we have so far blocked requests to over 90 domains for more than 17% of our Cloud Web Security (CWS) customers. Second, because we have seen it being used to distribute “Cryptowall”, the latest ransomware to follow in the success of the now infamous “Cryptolocker”. And third, because it continues the trend of an increased reliance upon Silverlight in EKs which we have previously written about for both the Fiesta and Angler kits. Like these other kits, we have seen RIG using malvertising to perform a drive-by attack on visitors to high profile, legitimate websites. This accounts for the high amount of traffic we have seen in the last month. Read More »

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Attack Analysis with a Fast Graph

TRAC-tank-vertical_logo-300x243This post is co-authored by Martin Lee, Armin Pelkmann, and Preetham Raghunanda.

Cyber security analysts tend to redundantly perform the same attack queries with different input data. Unfortunately, the search for useful meta-data correlation across proprietary and open source data sets may be laborious and time consuming with relational databases as multiple tables are joined, queried, and the results inevitably take too long to return. Enter the graph database, a fundamentally improved database technology for specific threat analysis functions. Representing information as a graph allows the discovery of associations and connection that are otherwise not immediately apparent.

Within basic security analysis, we represent domains, IP addresses, and DNS information as nodes, and represent the relationships between them as edges connecting the nodes. In the following example, domains A and B are connected through a shared name server and MX record despite being hosted on different servers. Domain C is linked to domain B through a shared host, but has no direct association with domain A.

graph_image_1 This ability to quickly identify domain-host associations brings attention to further network assets that may have been compromised, or assets that will be used in future attacks.

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Walking in a Winter Wonderland

It is not uncommon to see an anti-spam system catch >99% of the spam passing through it. Most of the best anti-spam systems catch >99.9% of spam. In this environment, spammers try just about anything to evade spam filters. Some spammers believe that blasting at high volume is the key to success. Others believe complete randomization of the message headers will confuse the anti-spam system. Still others take a minimalist approach, sending only a URL in the body. As anti-spam systems close gaps in their coverage, spammers are forced to find new tricks (or resort to variations on old tricks). It’s an arms race.

Screen-Shot-2014-05-24-at-5.24.29-AM-300x224One spam technique in particular is attracting more and more spammers. This technique is known in the email industry as “snowshoe” spam. Snowshoes are footwear that allows a person to walk over deep snow by distributing their weight over a larger surface area, thus preventing the wearer’s foot from sinking. But what do snowshoes have to do with unsolicited bulk email? In the email world “snowshoe” spam is unsolicited bulk email that is sent using a large number of IP addresses, and at a low message volume per IP address.

Cisco’s worldwide sensor network records details about a substantial quantity of spam. We analyze this large dataset for trends among senders. Below is a breakdown of spam by sender type. Note that the volume of snowshoe spam has more than doubled since November 2013.


Spam broken down by Sender Type

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