I. BACKGROUND
The Solaris runtime linker, ld.so.1(1), processes dynamic executables and shared objects at runtime, binding them to create a run-able 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. It is available at 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 E-mail 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.
