Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

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.
For Cybersecurity to Be Proactive, Terrains Must Be Mapped
Craig Harber, Chief Technology Officer at Fidelis Cybersecurity,  10/8/2019
A Realistic Threat Model for the Masses
Lysa Myers, Security Researcher, ESET,  10/9/2019
USB Drive Security Still Lags
Dark Reading Staff 10/9/2019
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
7 Threats & Disruptive Forces Changing the Face of Cybersecurity
This Dark Reading Tech Digest gives an in-depth look at the biggest emerging threats and disruptive forces that are changing the face of cybersecurity today.
Flash Poll
2019 Online Malware and Threats
2019 Online Malware and Threats
As cyberattacks become more frequent and more sophisticated, enterprise security teams are under unprecedented pressure to respond. Is your organization ready?
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-17593
PUBLISHED: 2019-10-14
JIZHICMS 1.5.1 allows admin.php/Admin/adminadd.html CSRF to add an administrator.
CVE-2019-17594
PUBLISHED: 2019-10-14
There is a heap-based buffer over-read in the _nc_find_entry function in tinfo/comp_hash.c in the terminfo library in ncurses before 6.1-20191012.
CVE-2019-17595
PUBLISHED: 2019-10-14
There is a heap-based buffer over-read in the fmt_entry function in tinfo/comp_hash.c in the terminfo library in ncurses before 6.1-20191012.
CVE-2019-14823
PUBLISHED: 2019-10-14
A flaw was found in the "Leaf and Chain" OCSP policy implementation in JSS' CryptoManager versions after 4.4.6, 4.5.3, 4.6.0, where it implicitly trusted the root certificate of a certificate chain. Applications using this policy may not properly verify the chain and could be vulnerable to...
CVE-2019-17592
PUBLISHED: 2019-10-14
The csv-parse module before 4.4.6 for Node.js is vulnerable to Regular Expression Denial of Service. The __isInt() function contains a malformed regular expression that processes large crafted input very slowly. This is triggered when using the cast option.