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iDEFENSE Security Advisory 07.29.03:
http://www.idefense.com/advisory/07.29.03.txt
Buffer Overflow in Sun Solaris Runtime Linker
July 29, 2003

I. BACKGROUND

The Solaris runtime linker, ld.so.1(1), processes dynamic executables
and shared objects at runtime, binding them to create a runnable
process. When LD_PRELOAD is set, the dynamic linker will use the
specified library before any other when searching for shared libraries.

II. DESCRIPTION

A locally exploitable buffer overflow exists in the ld.so.1 dynamic
runtime linker in Sun's Solaris operating system. The LD_PRELOAD
variable can be passed a large value, which will cause the runtime
linker to overflow a stack based buffer. The overflow occurs on a
non-executable stack making command execution more difficult than
normal, but not impossible. 

III. ANALYSIS

iDEFENSE has proof of concept exploit code allowing local attackers to
gain root privileges by exploiting the /usr/bin/passwd command on
Solaris 9. A "return to libc" method is utilized to circumvent the
safeguards of the non-executable stack. It is feasible for a local
attacker to exploit this vulnerability to gain root privileges if at
least one setuid root dynamically linked program exists on the system.
Virtually all default implementations of Solaris 8 and 9 fulfill this
criterion.

IV. DETECTION

The following operating system configurations are vulnerable:

SPARC Platform
     * Solaris 2.6 with patch 107733-10 and without patch 107733-11
     * Solaris 7 with patches 106950-14 through 106950-22 and without
       patch 106950-23
     * Solaris 8 with patches 109147-07 through 109147-24 and without
       patch 109147-25
     * Solaris 9 without patch 112963-09

   x86 Platform
     * Solaris 2.6 with patch 107734-10 and without patch 107734-11
     * Solaris 7 with patches 106951-14 through 106951-22 and without
       patch 106951-23
     * Solaris 8 with patches 109148-07 through 109148-24 and without
       patch 109148-25
     * Solaris 9 without patch 113986-05

V. VENDOR FIX

Sun has provided a fix for this issue available from: 
http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsalert/55680

VI. CVE INFORMATION

The Mitre Corp.'s Common Vulnerabilities and Exposures (CVE) Project
has assigned the identification number CAN-2003-0609 to this issue.

VII. DISCLOSURE TIMELINE

01 JUN 2003      Issue disclosed to security-alert@sun.com
02 JUN 2003      Response from Sun Security Coordination Team
03 JUN 2003      Email to Sun Security Coordination Team
04 JUN 2003      Issue disclosed to iDEFENSE
16 JUL 2003      Status Request to Sun Security Coordination Team
22 JUL 2003      Response from Sun Security Coordination Team
28 JUL 2003      iDEFENSE clients notified
29 JUL 2003      Coordinated Public Disclosure

VIII. CREDIT

Jouko Pynnonen (jouko@iki.fi) discovered this vulnerability.


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