Vulnerabilities / Threats
3/24/2016
04:45 PM
Connect Directly
Twitter
LinkedIn
RSS
E-Mail
50%
50%

Apple Zero-Day Flaw Leaves OS X Systems Vulnerable to Attack

All versions of OS X including El Capitan affected by bug, SentinelOne says

A security feature explicitly designed to prevent modifications to certain files and folders on Apple’s OS X El Capitan desktop operating system can not only be bypassed, but also actually be used to make malware harder to remove from an infected system.

That’s according to Pedro Vilaça, lead OS X security researcher at SentinelOne, who disclosed full details of the vulnerability at the SysCan360 conference in Singapore this week after first informing Apple of the issue.

The zero-day vulnerability exists in all versions of OS X including El Capitan. But it has been addressed in the latest update to the operating system (OS X 10.11.4) that Apple announced March 21. According to SentinelOne, patches will be available soon for the affected OS X versions.

A SentinelOne blog post described the flaw as a non-memory corruption bug that would allow an attacker to escalate privileges on a system and execute arbitrary code on it. Importantly, it allows an attacker to completely bypass System Integrity Protection (SIP), a security feature that Apple introduced with El Capitan last year.

SIP is supposed to prevent users, even those with root access, from modifying certain files and folders in the operating system. The feature is designed essentially to limit the ability of users to make potentially risky changes to their systems. But a weakness in how SIP has been implemented allows attackers a way to bypass it, says Vilaça who has developed an exploit showing how to exploit the flaw.

“The exploit can be used to control any entitlement given by Apple to a certain binary,” Vilaça said in comments to Dark Reading.  Apple has authorized certain binaries to make modifications so it can make needed updates to the system, he says. Those same binaries can be leveraged to get around SIP.

An attacker could use the exploit to load unauthorized kernel code on to a system so as to fully disable SIP protections inside the kernel, he says. The exploit allows code execution and sandbox escape without compromising the kernel so it is not detected by SIP, he says.  As a result, it could be exploited in state-sponsored and highly targeted attacks. 

To exploit the flaw however, an attacker would first need to find a way to compromise an OS X system. The flaw is not directly exploitable remotely, so an attacker would need to try and compromise a system first via a spearphishing attack or through a browser exploit.

By escalating privileges to root access, an attacker would have read and write privileges to all areas of the file system and potentially take control of the whole system, Vilaça said.

Guillaume Ross, senior security consultant at Rapid7 said the vulnerability that Vilaça disclosed this week is particularly problematic for systems administration who have to manage OS X servers used by multiple users via SSH or screen-sharing. “For shared OS X computers such as those found in schools, this vulnerability should be considered very dangerous, as legitimate users could attempt to use it to elevate privileges and take control of the system, or other users’ data,” he said in a statement.

“Privilege escalation bugs like this are often used as a second step – they come after an attack or where malware has taken control of the system,” he says. In order for such flaws to work, an attacker would need to find a way to leverage existing malware on a system or gain physical access to a system, he said.

The latest vulnerability is another indication that Apple’s technologies are not as immune to attacks as many generally believe.

Security vendor Cybereason Labs earlier this month published a report highlighting how the Mac OS X is as vulnerable to malicious attacks as other systems. Adversaries haven’t focused a whole lot on Mac malware because the platform’s market share is relatively low compared to Windows-based software. But just because fewer threats target OS X doesn’t mean it is immune to attacks, Cybereason senior security researcher, Amit Serper wrote in the report.

As examples, he pointed towards the recently disclosed KeRanger ransomware targeting Macs that was discovered by Palo Alto Networks and another flaw dubbed OceanLotus discovered by Qihoo 360, a Chinese firm.

“There are also zero-day attacks that exploit OS X and iOS 7, according to Hacking Team emails that emerged after the company was breached last July,” Serper reminded in his report. “Not to stoke security fears, but there may be other zero-day attacks as well.”

Related Content: 

 

Interop 2016 Las VegasFind out more about security threats at Interop 2016, May 2-6, at the Mandalay Bay Convention Center, Las Vegas. Click here for pricing information and to register.

Jai Vijayan is a seasoned technology reporter with over 20 years of experience in IT trade journalism. He was most recently a Senior Editor at Computerworld, where he covered information security and data privacy issues for the publication. Over the course of his 20-year ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Joe Stanganelli
50%
50%
Joe Stanganelli,
User Rank: Ninja
3/26/2016 | 9:22:57 AM
The obvious not so obvious
Re: "But just because fewer threats target OS X doesn't mean it is immune to attacks"

You know this.  I know this.  The rest of the security community knows this.

After about 14 years, it'd be nice if users realized this, too.
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win a Starbucks Card! Click Here
Latest Comment: This comment is waiting for review by our moderators.
Current Issue
DNS Threats: What Every Enterprise Should Know
Domain Name System exploits could put your data at risk. Here's some advice on how to avoid them.
Flash Poll
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2013-7445
Published: 2015-10-15
The Direct Rendering Manager (DRM) subsystem in the Linux kernel through 4.x mishandles requests for Graphics Execution Manager (GEM) objects, which allows context-dependent attackers to cause a denial of service (memory consumption) via an application that processes graphics data, as demonstrated b...

CVE-2015-4948
Published: 2015-10-15
netstat in IBM AIX 5.3, 6.1, and 7.1 and VIOS 2.2.x, when a fibre channel adapter is used, allows local users to gain privileges via unspecified vectors.

CVE-2015-5660
Published: 2015-10-15
Cross-site request forgery (CSRF) vulnerability in eXtplorer before 2.1.8 allows remote attackers to hijack the authentication of arbitrary users for requests that execute PHP code.

CVE-2015-6003
Published: 2015-10-15
Directory traversal vulnerability in QNAP QTS before 4.1.4 build 0910 and 4.2.x before 4.2.0 RC2 build 0910, when AFP is enabled, allows remote attackers to read or write to arbitrary files by leveraging access to an OS X (1) user or (2) guest account.

CVE-2015-6333
Published: 2015-10-15
Cisco Application Policy Infrastructure Controller (APIC) 1.1j allows local users to gain privileges via vectors involving addition of an SSH key, aka Bug ID CSCuw46076.

Dark Reading Radio
Archived Dark Reading Radio

The cybersecurity profession struggles to retain women (figures range from 10 to 20 percent). It's particularly worrisome for an industry with a rapidly growing number of vacant positions.

So why does the shortage of women continue to be worse in security than in other IT sectors? How can men in infosec be better allies for women; and how can women be better allies for one another? What is the industry doing to fix the problem -- what's working, and what isn't?

Is this really a problem at all? Are the low numbers simply an indication that women do not want to be in cybersecurity, and is it possible that more women will never want to be in cybersecurity? How many women would we need to see in the industry to declare success?

Join Dark Reading senior editor Sara Peters and guests Angela Knox of Cloudmark, Barrett Sellers of Arbor Networks, Regina Wallace-Jones of Facebook, Steve Christey Coley of MITRE, and Chris Roosenraad of M3AAWG on Wednesday, July 13 at 1 p.m. Eastern Time to discuss all this and more.