Posts Tagged: mac os x

Sep 14

‘Shellshock’ Bug Spells Trouble for Web Security

As if consumers weren’t already suffering from breach fatigue: Experts warn that attackers are exploiting a critical, newly-disclosed security vulnerability present in countless networks and Web sites that rely on Unix and Linux operating systems. Experts say the flaw, dubbed “Shellshock,” is so intertwined with the modern Internet that it could prove challenging to fix, and in the short run is likely to put millions of networks and countless consumer records at risk of compromise.

The bug is being compared to the recent Heartbleed vulnerability because of its ubiquity and sheer potential for causing havoc on Internet-connected systems — particularly Web sites. Worse yet, experts say the official patch for the security hole is incomplete and could still let attackers seize control over vulnerable systems.

The problem resides with a weakness in the GNU Bourne Again Shell (Bash), the text-based, command-line utility on multiple Linux and Unix operating systems. Researchers discovered that if Bash is set up to be the default command line utility on these systems, it opens those systems up to specially crafted remote attacks via a range of network tools that rely on it to execute scripts, from telnet and secure shell (SSH) sessions to Web requests.

According to several security firms, attackers are already probing systems for the weakness, and that at least two computer worms are actively exploiting the flaw to install malware. Jaime Blasco, labs director at AlienVault, has been running a honeypot on the vulnerability since yesterday to emulate a vulnerable system.

“With the honeypot, we found several machines trying to exploit the Bash vulnerability,” Blasco said. “The majority of them are only probing to check if systems are vulnerable. On the other hand, we found two worms that are actively exploiting the vulnerability and installing a piece of malware on the system. This malware turns the systems into bots that connect to a C&C server where the attackers can send commands, and we have seen the main purpose of the bots is to perform distributed denial of service attacks.”

The vulnerability does not impact Microsoft Windows users, but there are patches available for Linux and Unix systems. In addition, Mac users are likely vulnerable, although there is no official patch for this flaw from Apple yet. I’ll update this post if we see any patches from Apple.

Update, Sept. 29 9:06 p.m. ET: Apple has released an update for this bug, available for OS X Mavericks, Mountain Lion, and Lion.

The U.S.-CERT’s advisory includes a simple command line script that Mac users can run to test for the vulnerability. To check your system from a command line, type or cut and paste this text:

env x='() { :;}; echo vulnerable' bash -c "echo this is a test"

If the system is vulnerable, the output will be:

 this is a test

An unaffected (or patched) system will output:

 bash: warning: x: ignoring function definition attempt
 bash: error importing function definition for `x'
 this is a test

US-CERT has a list of operating systems that are vulnerable. Red Hat and several other Linux distributions have released fixes for the bug, but according to US-CERT the patch has an issue that prevents it from fully addressing the problem. Continue reading →

Apr 13

Who Wrote the Flashback OS X Worm?

A year ago today, Apple released a software update to halt the spread of the Flashback worm, a malware strain that infected more than 650,000 Mac OS X systems using a vulnerability in Apple’s version of Java. This somewhat dismal anniversary is probably as good a time as any to publish some clues I’ve gathered over the past year that point to the real-life identity of the Flashback worm’s creator.

mavookiconBefore I delve into the gritty details, a little background on this insidious contagion is in order. A keenly detailed research paper (PDF) published last year by Finnish security firm F-Secure puts the impact and threat from Flashback in perspective, noting that the malware boasted a series of “firsts” for its kind. For starters, Flashback was the first OS X malware to be “VMware aware” — or to know when it was being run in a virtual environment (a trick designed to frustrate security researchers). It also was the first to disable XProtect, OS X’s built-in malware protection program. These features, combined with its ability to spread through a then-unpatched vulnerability in Java made Flashback roughly as common for Macs as the Conficker Worm was for Windows PCs.

“This means Flashback is not only the most advanced, but also the most successful OS X malware we’ve ever seen,” wrote F-Secure’s Broderick Ian Aquilino.

The F-Secure writeup answers an important question not found in other analyses: Namely, what was the apparent intended purpose of Flashback? Put simply: to redirect Google results to third-party advertisers, all for the author’s profit. It’s name was derived from the fact that it spread using a social engineering trick of presenting the OS X user with a bogus Flash Player installation prompt. F-Secure notes that this same behavior — both the Flash social engineering trick and the redirection to fake Google sites that served search results for third-party advertisers that benefited the author — was also found in the QHost malware, suggesting that Flashback may have been the next evolution of the Mac QHost malware.


A year ago, I published a series that sought to identify the real-life hackers behind the top spam botnets. Using much the same methodology, I was able to identify and locate a young man in Russia who appears (and privately claims) to be the author of Flashback. As it happens, this individual hangs out on many of the same forums as the world’s top spammers (but more on that at another time).

Given Flashback’s focus on gaming Google’s ad networks, I suspected that the worm’s author probably was a key member of forums that focus on so-called “black hat SEO,” (search engine optimization), or learned in illicit ways to game search engines and manipulate ad revenues. Sure enough, this individual happens to be a very active and founding member of, a closely guarded Russian language forum dedicated to this topic.

Below is a screen shot taken from a private message between a “VIP” user named “Mavook” and a top forum member on The conversation took place on July 14, 2012. A rough translation of their conversation is superimposed on the redacted screen grab, but basically it shows Mavook asking the senior member for help in gaining access to, a fairly exclusive English-language cybercrime forum (and one that I profiled in a story earlier this week). VIP member "Mavook" claims responsibility for creating Flashback to a senior forum member. member “Mavook” claims responsibility for creating Flashback to a senior forum member.

Mavook asks the other member to get him an invitation to Darkode, and Mavook is instructed to come up with a brief bio stating his accomplishments, and to select a nickname to use on the forum if he’s invited. Mavook replies that the Darkode nick should be not be easily tied back to his BlackSEO persona, and suggests the nickname “Macbook.” He also states that he is the “Creator of Flashback botnet for Macs,” and that he specializes in “finding exploits and creating bots.”

Continue reading →

Mar 13

Critical Updates for Windows, Adobe Flash, Air

Microsoft and Adobe each released patches today to plug critical security holes in their products. Microsoft issued seven update bundles to address at least 19 20 vulnerabilities in Windows and related software. Adobe released the fourth security update in nearly as many weeks for its Flash Player software, as well as a fix for Adobe AIR.

winiconMicrosoft today began pushing out seven security patches, four of them rated “critical,” meaning the flaws they fix could be used by malware or bad guys to break into unpatched systems with little or no help from users. The critical patches address bugs in Windows, Internet Explorer, Microsoft Silverlight, Microsoft Office and Microsoft SharePoint. Updates are available for Windows XP, Vista, Windows 7, Windows 8, Windows Server 2003, 2008 and 2012.

More information on the Microsoft patches is available at the Microsoft security response center blog, which also discusses some changes to the way security updates are applied to apps available through the Windows Store.

Continue reading →

Apr 12

Correction to Java Update Story

An earlier version of this blog post incorrectly stated that Oracle had shipped security updates for its Java software. Oracle did push out an update for Java earlier this month — Java 6 Update 32 — but the new version was a maintenance update that did not include security fixes. My apologies for any confusion this may have caused.

Apr 12

Adobe, Microsoft Issue Critical Updates

Adobe and Microsoft today each issued critical updates to plug security holes in their products. The patch batch from Microsoft fixes at least 11 flaws in Windows and Windows software. Adobe’s update tackles four vulnerabilities that are present in current versions of Adobe Acrobat and Reader.

Seven of the 11 bugs Microsoft fixed with today’s release earned its most serious “critical” rating, which Microsoft assigns to flaws that it believes attackers or malware could leverage to break into systems without any help from users. In its security bulletin summary for April 2012, Microsoft says it expects miscreants to quickly develop reliable exploits capable of leveraging at least four of the vulnerabilities. Continue reading →

Nov 11

Public Java Exploit Amps Up Threat Level

An exploit for a recently disclosed Java vulnerability that was previously only available for purchase in the criminal underground has now been rolled into the open source Metasploit exploit framework. Metasploit researchers say the Java attack tool has been tested to successfully deliver payloads on a variety of platforms, including the latest Windows, Mac and Linux systems.

On Monday, I disclosed how the Java exploit is being sold on cybercrime forums and incorporated into automated crimeware kits like BlackHole. Since then, security researchers @_sinn3r and Juan Vasquez have developed a module for Metasploit that makes the attack tool available to penetration testers and malicious hackers alike. According to a post on the Metasploit blog today, the Java vulnerability “is particularly pernicious, as it is cross-platform, unpatched on some systems, and is an easy-to-exploit client-side that does little to make the user aware they’re being exploited.

Metasploit also posted the results of testing the exploit against a variety of browsers and platforms, and found that it worked almost seamlessly to compromise systems across the board, from the latest 64-bit Windows 7 machines to Mac OS X and even Linux systems.

This development should not be taken lightly by any computer user. According to Sun’s maker Oracle, more than three billion devices run Java. What’s more, Java vulnerabilities are by some accounts the most popular exploit paths for computer crooks these days. On Monday, Microsoft’s Tim Rains published a blog post noting that the most commonly observed type of exploits in the first half of 2011 were those targeting vulnerabilities in Oracle (formerly Sun Microsystems) Java Runtime Environment (JRE), Java Virtual Machine (JVM), and Java SE in the Java Development Kit (JDK).

Continue reading →

May 11

‘Weyland-Yutani’ Crime Kit Targets Macs for Bots

A new crimeware kit for sale on the criminal underground makes it a simple point-and-click exercise to develop malicious software designed to turn Mac OSX computers into remotely controllable zombie bots. According to the vendor of this kit, it is somewhat interchangeable with existing crimeware kits made to attack Windows-based PCs.

The Mac malware builder in action.

KrebsOnSecurity has spilled a great deal of digital ink covering the damage wrought by ZeuS and SpyEye, probably the most popular crimeware kits built for Windows. A crimeware kit is a do-it-yourself package of tools that allow users to create custom versions of a malicious software strain capable of turning machines into bots that can be remotely controlled and harvested of financial and personal data. The bot code, generated by the crimeware kit’s “builder” component, typically is distributed via social engineering attacks in email and social networking sites, or is foisted by an exploit pack like Eleonore or Blackhole, which use hacked Web sites and browser flaws to quietly install the malware. Crimeware kits also come with a Web-based administration panel that allows the customer to manage and harvest data from infected PCs.

Crimekit makers have focused almost exclusively on the Windows platform, but today Danish IT security firm CSIS Security Group blogged about a new kit named the Weyland-Yutani BOT that is being marketed as the first of its kind to attack the Mac OS X platform.

The seller of this crimeware kit claims his product supports form-grabbing in Firefox and Chrome, and says he plans to develop a Linux version and one for the iPad in the months ahead. The price? $1,000, with payment accepted only through virtual currencies Liberty Reserve or WebMoney.

The CSIS blog post contains a single screen shot of this kit’s bot builder, and references a demo video but doesn’t show it. I wanted to learn more about this kit, and so contacted the seller via a Russian language forum where he was advertising his wares.

The author said he is holding off on including Safari form-grabbing capability for now, complaining that there are “too many problems in that browser.” Still, he was kind enough to share a copy of a video that shows the kit’s builder and admin panel in action. Click the video link below to check that out.

ZeuS and SpyEye are popular in part because they support a variety of so-called “Web injects,” third-party plug-ins that let botmasters manipulate the content that victims see in their Web browsers. The most popular Web injects are designed to slightly alter the composition of various online banking Web sites in a bid to trick the victim customer into supplying additional identifying information that can be used later on to more fully compromise or hijack the account. According to the author, Web injects developed for ZeuS and SpyEye also are interchangeable with this Mac crimekit. “They need to be formatted and tagged, but yes, you can use Zeus injects with this bot,” he told me in an instant message conversation.

Continue reading →

Oct 10

Java Update Clobbers 29 Security Flaws

Oracle today released a critical update to its widely-installed Java software, fixing at least 29 security vulnerabilities in the program.

Most consumers on Microsoft Windows PCs will have some version of Java installed (if you’re not sure whether you have Java or what version might be installed, click this link). Existing users can grab the latest version — Java 6 Update 22 — by visiting the Windows Control Panel, clicking on the Java icon, and then selecting the “Update Now” button on the “Update” tab. If you don’t already have this software, I recommend that you keep it that way.

Per Oracle’s advisory, updates are available for Windows, Solaris and Linux versions of Java. Apple maintains its own version of Java for OS X systems, and typically issues fixes for its version several months after the official Java release.

Be aware that Java’s updater may by default also include free “extras” that you may not want, such as the Yahoo! Toolbar or whatever other moneymaker they decide to bundle with their software this time around, so be sure to de-select that check box during installation if you don’t want the add-ons.

Aug 10

Adobe, Apple Issue Security Updates

Both Adobe and Apple have released security updates or alerts in the past 24 hours. Adobe pushed out a critical patch that fixes at least 20 vulnerabilities in its Shockwave Player, while Apple issued updates to correct 13 flaws in Mac OS X systems.

The Adobe patch applies to Shockwave Player and earlier on Windows and Mac operating systems. Adobe recommends that users upgrade to Shockwave Player, available at this link. But before you do that, you might want to visit this link, which will tell you whether or not you need to update, and indeed whether you currently have Shockwave installed at all. If you visit it and don’t see an animation, then you don’t have Shockwave (and probably aren’t missing it either).

One other note about Shockwave: Firefox users may notice a “Shockwave Flash” entry when they click “Tools,” “Add-0ns,” and then the “Plugins” tab. For reasons that are too complicated to explain in one breath, this is actually Adobe’s name for its regular Flash player, which most people probably do want installed because can be difficult to browse and use the Internet without it.  By the way, if you haven’t updated your Flash Player in a while, Adobe issued a new version of that software on Aug 10 that plugged a half dozen security holes.

Apple’s update affects Mac OS X Server 10.5, Mac OS X 10.5.8 , Mac OS X Server 10.6 , Mac OS X 10.6.4 and is available via Software Update or from Apple Downloads.

Jun 10

Microsoft, Apple Ship Big Security Updates

In its largest patch push so far this year, Microsoft today released 10 security updates to fix at least 34 security vulnerabilities in its Windows operating system and software designed to run on top of it. Separately, Apple has shipped another version of Safari for both Mac and Windows PCs that plugs some four dozen security holes in the Web browser.

Microsoft assigned three of the updates covering seven vulnerabilities a “critical” rating, meaning they can be exploited to help attackers break into vulnerable systems with no help from users. At least 14 of the flaws fixed in this month’s patch batch are in Microsoft Excel, and another eight relate to Windows and Internet Explorer.

According to Microsoft, the most serious of the bugs involves a weakness in the way Windows handles certain media formats, and is present in all supported versions of Windows. Another critical update nixes six different insecure ActiveX controls (plug-ins for Internet Explorer), while the third critical update corrects at least a half dozen vulnerabilities in IE.

Microsoft notes that Office XP users may not be able to install one of the needed updates; Rather, Redmond is releasing what it calls a “shim,” or essentially and point-and-click “FixIt” tool that apparently does the job. If you use Office XP, go ahead and click the “FixIt” icon at this link when you’re done installing the rest of the updates.

The Microsoft patches are available through Windows Update or via Automatic Update. As usual, please drop a note in the comments below if you experience any problems as a result of installing these updates.

Apple’s Safari 5.0 update fixes at least four-dozen security vulnerabilities in Safari on Mac OS X and Windows versions. Updates are available for Mac OS X v 10.4.11, Mac OS X v10.5.8, Mac OS X v10.6.2 or later, Windows 7, Vista, and XP. Mac users can grab the update from Software Update or Apple Downloads; Safari users on Windows will need to update using the bundled Apple Software Update utility.