Posts Tagged: linux


25
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. Jamie 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:

vulnerable
 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 →


7
Feb 13

Critical Flash Player Update Fixes 2 Zero-Days

Adobe today pushed out an emergency update that fixes at least two zero-day vulnerabilities in its ubiquitous Flash Player software — flaws that attackers are already exploiting to break into systems. Interestingly, Adobe warns that one of the exploits in use is designed to drop malware on both Windows and Mac OS X systems.

brokenflash-aAdobe said in an advisory that one of the vulnerabilities — CVE-2013-0634 – is being exploited in the wild in attacks delivered via malicious Flash content hosted on websites that target Flash Player in Firefox or Safari on the Macintosh platform, as well as attacks designed to trick Windows users into opening a Microsoft Word document delivered as an email attachment.

Adobe also warned that a separate flaw — CVE-2013-0633 — is being exploited in the wild in targeted attacks designed to trick the user into opening a Microsoft Word document delivered as an email attachment which contains malicious Flash content. The company said the exploit for CVE-2013-0633 targets the ActiveX version of Flash Player on Windows (i.e. Internet Explorer users).

Updates are available for Windows, Mac, Linux and Android users. The latest Windows and Mac version is v. 11.5.502.149, and is available from this link. Those who prefer a direct link to the OS-specific downloads can grab them here. To find out if you have Flash installed and what version your browser may be running, check out this page.

flash115502149

Flash Player installed with Google Chrome should automatically be updated to the latest Google Chrome version, which will include Adobe Flash Player v. 11.5.31.139 for Windows, Macintosh and Linux. Likewise, Internet Explorer 10 for Windows 8 also includes an auto-update feature, which should bring Flash to version 11.3.379.14 for Windows.

Adobe’s advisory notes that the vulnerability that has been used to attack both Mac and Windows users was reported with the help of the Shadowserver Foundation, the federally funded technology research center MITRE Corporation, and aerospace giant Lockheed Martin‘s computer incident response team. No doubt there are some interesting stories about how these attacks were first discovered, and against whom they were initially deployed.


30
Aug 12

Security Fix for Critical Java Flaw Released

Oracle has issued an urgent update to close a dangerous security hole in its Java software that attackers have been using to deploy malicious software. The patch comes amid revelations that Oracle was notified in April about this vulnerability and a number other other potentially unpatched Java flaws.

The patch fixes a critical flaw in the latest version of Java 7 that is now being widely exploited. Users with vulnerable versions of Java installed can have malware silently planted on their systems just by browsing to a hacked or malicious Web site.

The update brings Java 7 to Update 7, and appears to fix the flaw being exploited and several other security holes. Oracle also released a security update for systems running Java 6, which brings that version to Java 6 Update 35.

Today’s patches are emergency, out-of-schedule updates for Oracle, which previously was not planning to release security updates for Java until October. Although it may appear that Oracle responded swiftly to the discovery of extremely dangerous flaws in its software, Security Explorations — a research firm from Poland — says it alerted Oracle about this vulnerability and 30 others back in April. It’s not yet clear how many of those vulnerabilities were patched in this release.

“We … expected that the most serious of them would be fixed by June 2012 Java CPU,” said Security Explorations CEO and founder Adam Gowdiak told The Register’s Neil McAllister. “But it didn’t happen and Oracle left many issues unpatched with plans to address them in the next Java [updates].”

Continue reading →


4
May 12

Critical Flash Update Fixes Zero-day Flaw

Adobe Systems Inc. today issued a security update to its Flash Player software. The company stressed that the update fixes a critical vulnerability that malicious actors have been using in targeted attacks.

Adobe classifies a security flaw as critical if it can be used to break into vulnerable machines without any help from users. The company said the vulnerability (CVE-2012-0779) fixed in the version released today has been exploited in targeted attacks designed to trick the user into clicking on a malicious file delivered in an email message, and that the exploit used in the attacks seen so far target Flash Player on Internet Explorer for Windows only.

Nevertheless, there are updates available for Flash Player versions designed for all operating systems that Adobe supports, including Mac, Linux and Android devices.

Continue reading →


14
Jun 11

Adobe Ships Security Patches, Auto-Update Feature

Adobe today issued more than a dozen security updates for its Acrobat and PDF Reader programs, including a feature update that will install future Reader security updates automatically. In addition, Adobe has shipped yet another version of its Flash Player software to fix a critical security flaw.

No doubt some will quibble with Adobe’s move toward auto-updating Reader: There is always a contingent in the user community who fear automatic updates will at some point force a faulty patch. But for better or worse, Adobe’s Reader software is the PDF reader software of choice for a majority of Windows computers in use today. Faced with incessant malware attacks against outdated versions of these programs, it seems irresponsible for Adobe to do anything other than offer auto-update capability to to Reader users more aggressively.

Adobe debuted this feature in April 2010, but at that the time Adobe decided to continue to honor whatever update option users had selected (the default has always been “download all updates automatically and notify me when they are ready to be installed”). With this latest update, Adobe will again prompt users to approve an auto-update choice, except this time the option pre-selected will be “Install Updates Automatically.”

Continue reading →


16
May 11

Something Old is New Again: Mac RATs, CrimePacks, Sunspots & ZeuS Leaks

New and novel malware appears with enough regularity to keep security researchers and reporters on their toes. But, often enough, there are seemingly new perils that  really are just old threats that have been repackaged or stubbornly lingering reports that are suddenly discovered by a broader audience. One of the biggest challenges faced by  the information security community is trying to decide which threats are worth investigating and addressing.  To illustrate this dilemma, I’ve analyzed several security news headlines that readers forwarded  to me this week, and added a bit more information from my own investigations.

I received more than two dozen emails and tweets from readers calling my attention to news that the source code for the 2.0.8.9 version of the ZeuS crimekit has been leaked online for anyone to download. At one point last year, a new copy of the ZeuS Trojan with all the bells and whistles was fetching at least $10,000. In February, I reported that the source code for the same version was being sold on underground forums. Reasonably enough, news of the source leak was alarming to some because it suggests that even the most indigent hackers can now afford to build their own botnets.

A hacker offering to host and install a control server for a ZeuS botnet.

We may see an explosion of sites pushing ZeuS as a consequence of this leak, but it hasn’t happened yet. Roman Hüssy, curator of ZeusTracker, said in an online chat, “I didn’t see any significant increase of new ZeuS command and control networks, and I don’t think this will change things.” I tend to agree. It was already ridiculously easy to start your own ZeuS botnet before the source code was leaked. There are a number of established and relatively inexpensive services in the criminal underground that will sell individual ZeuS binaries to help novice hackers set up and establish ZeuS botnets (some will even sell you the bulletproof hosting and related amenities as part of a package), for a fraction of the price of the full ZeuS kit.

My sense is that the only potential danger from the release of the ZeuS source code  is that more advanced coders could use it to improve their current malware offerings. At the very least, it should encourage malware developers to write more clear and concise user guides. Also, there may be key information about the ZeuS author hidden in the code for people who know enough about programming to extract meaning and patterns from it.

Are RATs Running Rampant?

Last week, the McAfee blog included an interesting post about a cross-platform “remote administration tool” (RAT) called IncognitoRAT that is based on Java and can run on Linux, Mac and Windows systems. The blog post featured some good details on the functionality of this commercial crimeware tool, but I wanted to learn more about how well it worked, what it looks like, and some background on the author.

Those additional details, and much more, were surprisingly easy to find. For starters, this RAT has been around in one form or another since last year. The screen shot below shows an earlier version of IncognitoRAT being used to remotely control a Mac system.

IncognitoRAT used to control a Mac from a Windows machine.

The kit also includes an app that allows customers to control botted systems via jailbroken iPhones.

Incognito ships with an app that lets customers control infected computers from an iPhone

The following video shows this malware in action on a Windows system. This video was re-recorded from IncognitoRAT’s YouTube channel (consequently it’s a little blurry), but if you view it full-screen and watch carefully you’ll see a sequence in the video that shows how the RAT can be used to send e-mail alerts to the attacker. The person making this video is using Gmail; we can see a list of his Gchat contacts on the left; and his IP address at the bottom of the screen.  That IP traces back to a Sympatico broadband customer in Toronto, Canada, which matches the hometown displayed in the YouTube profile where this video was hosted. A Gmail user named “Carlo Saquilayan” is included in the Gchat contacts visible in the video.

Continue reading →


13
May 11

Critical Flash Player Update Plugs 11 Holes

Adobe has released another batch of security updates for its ubiquitous Flash Player software. This “critical” patch fixes at least 11 vulnerabilities, including one that reports suggest is being exploited in targeted email attacks.

In the advisory that accompanies this update, Adobe said “there are reports of malware attempting to exploit one of the vulnerabilities, CVE-2011-0627, in the wild via a Flash (.swf) file embedded in a Microsoft Word (.doc) or Microsoft Excel (.xls) file delivered as an email attachment targeting the Windows platform. However, to date, Adobe has not obtained a sample that successfully completes an attack.”

The vulnerabilities exist in Flash versions 10.2.159.1 and earlier for Windows, Mac, Linux and Solaris. To learn which version of Flash you have, visit this link. The new version for most platforms is 10.3.181.14; Android users should upgrade to Flash Player 10.3.185.21 available by browsing to the Android Marketplace on an Android phone; Google appears to have updated Chrome users automatically with this version of Flash back on May 6 (Chrome versions 11.0.696.68 and later have the newest Flash version).

Continue reading →


30
Mar 11

Test Your Browser’s Patch Status

With new security updates from vendors like Adobe, Apple and Java coming out on a near-monthly basis, keeping your Web browser patched against the latest threats can be an arduous, worrisome chore. But a new browser plug-in from security firm Qualys makes it quick and painless to identify and patch outdated browser components.

Qualys Browser Check plug-inThe Qualys BrowserCheck plug-in works across multiple browsers — including Internet Explorer, Firefox, Chrome and Opera, on multiple operating systems. Install the plug-in, restart the browser, click the blue “Scan Now” button, and the results should let you know if there are any security or stability updates available for your installed plug-ins (a list of the plug-ins and add-ons that this program can check is available here). Clicking the blue “Fix It” button next to each action item listed fetches the appropriate installer from the vendor’s site and prompts you to download and install it. Re-scan as needed until the browser plug-ins are up to date.

Secunia has long had a very similar capability built into its free Personal Software Inspector program, but I realize not everyone wants to install a new program + Windows service to stay abreast of the latest patches (Secunia also offers a Web-based scan, but it requires Java, a plug-in that I have urged users to ditch if possible). The nice thing about Qualys’ plug-in approach is that it works not only on Windows, but also on Mac and Linux machines. On Windows 64-bit systems, only the 32-bit version of Internet Explorer is supported, and the plug-in thankfully nudges IE6 and IE7 users to upgrade to at least IE8.

Having the latest browser updates in one, easy-to-manage page is nice, but remember that the installers you download may by default come with additional programs bundled by the various plug-in makers. For example, when I updated Adobe’s Shockwave player on my test machine, the option to install  Registry Mechanic was pre-checked. The same thing happened when I went to update my Foxit Reader plug-in, which wanted to set Ask.com as my default search provider, set ask.com as my home page, and have the Foxit toolbar added.


12
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.


8
Aug 10

Foxit Fix for “Jailbreak” PDF Flaw

One of the more interesting developments over the past week has been the debut of jailbreakme.com, a Web site that allows Apple customers to jailbreak their devices merely by visiting the site with their iPhone, iPad or iTouch. Researchers soon learned that the page leverages two previously unknown security vulnerabilities in the PDF reader functionality built into Apple’s iOS4.

Adobe was quick to issue a statement saying that the flaws were in Apple’s software and did not exist in its products. Interestingly, though, this same attack does appear to affect Foxit Reader, a free PDF reader that I often recommend as an alternative to Adobe.

According to an advisory Foxit issued last week, Foxit Reader version 4.1.1.0805 “fixes the crash issue caused by the new iPhone/iPad jailbreak program which can be exploited to inject arbitrary code into a system and execute it there.” If you use Foxit, you grab the update from within the application (“Help,” then “Check for Updates Now”) or from this link.

Obviously, from a security perspective the intriguing aspect of a drive-by type jailbreak is that such an attack could easily be used for more nefarious purposes, such as seeding your iPhone with unwanted software. To be clear, nobody has yet seen any attacks like this, but it’s certainly an area to watch closely. F-Secure has a nice Q&A about the pair of PDF reader flaws that allow this attack, and what they might mean going forward. Apple says it plans to release an update to quash the bugs.

I’m left wondering what to call these sorts of vulnerabilities that quite obviously give users the freedom that jailbreaking their device(s) allows (the ability to run applications that are not approved and vetted by Apple) but that necessarily direct the attention of attackers to very potent vulnerabilities that can be used to target jailbreakers and regular users alike. It’s not quite a “featureability,” which describes an intentional software component that opens up customers to attack even as the vendor insists the feature is a useful, by-design ability rather than a liability.

I came up with a few ideas.

– “Apptack”

– “Jailbait” (I know, I know, but it’s catchy)

– “Freedoom”

Maybe KrebsOnSecurity readers can devise a better term? Sound off in the comments below if you come up with any good ones.

Finally, I should note that while Adobe’s products may not be affected by the above-mentioned flaws, the company said last week that it expects to ship an emergency update on Tuesday to fix at least one critical security hole present in the latest version of Adobe Reader for Windows, Mac and Linux systems.

Adobe said the update will fix a flaw that researcher Charlie Miller revealed (PDF!) at last month’s Black Hat security conference in Las Vegas, but it hinted that the update may also include fixes for other flaws. I’ll have more on those updates when they’re released, which should coincide with one of the largest Microsoft Patch Tuesdays ever: Redmond said last week that it expects to issue at least 14 updates on Tuesday. Update, Aug. 10, 5:06 p.m. ET:Adobe won’t be releasing the Reader update until the week of Aug. 16.