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
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