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NSFOCUS Security Advisory(SA2003-02)
Topic: Solaris lpq Stack Buffer Overflow Vulnerability
Release Date: 2003-3-31
CVE CAN ID: CAN-2003-0091
Sun Solaris 2.5.1 (SPARC/x86) Sun Solaris 2.6 (SPARC/x86) Sun Solaris 7 (SPARC/x86)
NSFOCUS Security Team has found a buffer overflow vulnerability in lpq, an application in Sun Solaris system. Exploiting the vulnerability local attackers could gain root privilege.
lpq, which is used to display the contents in printing queue, is a command in SunOS/BSD compatible package.By default suid root bit is set to it. Because valid bound check has not been implemented when handling the data provided by users, attackers could cause a fixed stack buffer to overflow. By carefully crafting overflow data attackers could run arbitrary code with root privilege.
Actually /usr/ucb/lpq is a symbol link to /usr/bin/lpstat. lpstat will operate according to the program names during the calling. If "lpq", it will operate in BSD style, or it will operate in System V style. The bsd_queue() function in lpq will call strcat() to copy the data provided by users to a buffer the size of which is fixed. Because the length of the copied data has not been checked, if an attacker provides a over-long string, he/she will cause a stack buffer overflow. By overwriting the returning addresses and other data in the stack, local attackers could gain root privilege.
Solaris 8/9 uses strlcat() to implement string copy, so it avoids buffer overflow and therefore is not vulnerable to the issue.
NSFOCUS suggests to disable suid root attribute of lpstat(lpq) temporarily: # chmod a-s /usr/bin/lpstat
2002-12-11 Informed the vendor. 2002-12-13 The vendor confirmed the vulnerability. 2003-03-31 The vendor released a Sun Alert and patches for this issue.
The Sun Alert is available at: http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doc=fsalert/52443
The patches are:
Solaris 2.6 106235-12 Solaris 2.6_x86 106236-12 Solaris 7 107115-12 Solaris 7_x86 107116-12
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2003-0091 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. Candidates may change significantly before they become official CVE entries.
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