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ECURITY FIX for CVE-2009-0217 (XML Signature HMAC Truncation Spoofing)

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patch extracted from mono 2.4.2.2
This commit is contained in:
jasper 2009-07-21 13:51:41 +00:00
parent 33f694372f
commit e4e2d96dc1
2 changed files with 47 additions and 2 deletions
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4
lang/mono/Makefile
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@ -1,11 +1,11 @@
# $OpenBSD: Makefile,v 1.9 2009/03/15 02:19:31 kurt Exp $
# $OpenBSD: Makefile,v 1.10 2009/07/21 13:51:41 jasper Exp $
ONLY_FOR_ARCHS= amd64 i386
COMMENT= cross platform, open source .NET developement framework
DISTNAME= mono-2.0
PKGNAME= ${DISTNAME}p5
PKGNAME= ${DISTNAME}p6
CATEGORIES= lang devel
SHARED_LIBS= mono-profiler-aot 0.0 \

45
lang/mono/patches/patch-mcs_class_System_Security_System_Security_Cryptography_Xml_SignedXml_cs Normal file
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@ -0,0 +1,45 @@
$OpenBSD: patch-mcs_class_System_Security_System_Security_Cryptography_Xml_SignedXml_cs,v 1.1 2009/07/21 13:51:41 jasper Exp $
Security fix for CVE-2009-0217, XML signature HMAC truncation authentication bypass
--- mcs/class/System.Security/System.Security.Cryptography.Xml/SignedXml.cs.orig Tue Jul 21 15:18:58 2009
+++ mcs/class/System.Security/System.Security.Cryptography.Xml/SignedXml.cs Tue Jul 21 15:20:54 2009
@@ -592,17 +592,28 @@ namespace System.Security.Cryptography.Xml {
return false;
byte[] actual = macAlg.ComputeHash (s);
- // HMAC signature may be partial
+ // HMAC signature may be partial and specified by <HMACOutputLength>
if (m_signature.SignedInfo.SignatureLength != null) {
- int length = actual.Length;
- try {
- // SignatureLength is in bits
- length = (Int32.Parse (m_signature.SignedInfo.SignatureLength) >> 3);
- }
- catch {
- }
+ int length = Int32.Parse (m_signature.SignedInfo.SignatureLength);
+ // we only support signatures with a multiple of 8 bits
+ // and the value must match the signature length
+ if ((length & 7) != 0)
+ throw new CryptographicException ("Signature length must be a multiple of 8 bits.");
- if (length != actual.Length) {
+ // SignatureLength is in bits (and we works on bytes, only in multiple of 8 bits)
+ // and both values must match for a signature to be valid
+ length >>= 3;
+ if (length != m_signature.SignatureValue.Length)
+ throw new CryptographicException ("Invalid signature length.");
+
+ // is the length "big" enough to make the signature meaningful ?
+ // we use a minimum of 80 bits (10 bytes) or half the HMAC normal output length
+ // e.g. HMACMD5 output 128 bits but our minimum is 80 bits (not 64 bits)
+ int minimum = Math.Max (10, actual.Length / 2);
+ if (length < minimum)
+ throw new CryptographicException ("HMAC signature is too small");
+
+ if (length < actual.Length) {
byte[] trunked = new byte [length];
Buffer.BlockCopy (actual, 0, trunked, 0, length);
actual = trunked;