iDefense Security Advisory 07.20.06: Sun Microsystems Solaris sysinfo() Kernel Memory Disclosure Vulnerability

Sun Microsystems Solaris sysinfo() Kernel Memory Disclosure Vulnerability

iDefense Security Advisory 07.20.06
http://www.idefense.com/application/poi/display?type=vulnerabilities
July 20, 2006

I. BACKGROUND

Solaris is a UNIX operating system developed by Sun Microsystems.

II. DESCRIPTION

Local exploitation of an integer overflow vulnerability in Sun
Microsystems Inc. Solaris allows attackers to read kernel memory from a
non-privileged userspace process.

The vulnerability specifically exists due to an integer overflow in
/usr/src/uts/common/syscall/systeminfo.c. The vulnerable code is as
follows:

125 if (kstr != NULL) {
126 if ((strcnt = strlen(kstr)) >= count) {
127 getcnt = count - 1;
128 if (subyte(buf + count - 1, 0) < 0)
129 return (set_errno(EFAULT));
130 } else
131 getcnt = strcnt + 1;
132 if (copyout(kstr, buf, getcnt))
133 return (set_errno(EFAULT));
134 return (strcnt + 1);
135 }

If the variable count (which is a value provided by the user invoking
the function) is 0, the function will call the copyout function with a
length argument of -1. Because copyout interprets the length argument as
an unsigned integer, a large amount of data will be copied out to
userspace, well beyond the boundaries that are intended.

III. ANALYSIS

Successful exploitation of this vulnerability allows attackers to read
sensitive kernel memory. This can lead to the compromise of passwords or
keys. It can also aid an attacker in gathering information for
exploitation of other kernel level vulnerabilities.

IV. DETECTION

iDefense has confirmed that Solaris 10 is vulnerable. Earlier versions
of Solaris are not affected.

V. WORKAROUND

iDefense is currently unaware of any workaround for this issue.

VI. VENDOR RESPONSE

Sun Alert ID 102343 addresses this issue and is available at:

http://sunsolve.sun.com/search/document.do?assetkey=1-26-102343-1

VII. CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.

VIII. DISCLOSURE TIMELINE

12/15/2005 Initial vendor notification
12/15/2005 Initial vendor response
07/20/2006 Coordinated public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.