Bug 479655 - (CVE-2009-0125) CVE-2009-0125 libnasl: OpenSSL incorrect checks for malformed signatures
CVE-2009-0125 libnasl: OpenSSL incorrect checks for malformed signatures
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
All Linux
high Severity high
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Assigned To: Red Hat Product Security
: Security
Depends On:
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Reported: 2009-01-12 06:34 EST by Jan Lieskovsky
Modified: 2009-01-23 21:41 EST (History)
1 user (show)

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Doc Type: Bug Fix
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Last Closed: 2009-01-22 03:33:35 EST
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Description Jan Lieskovsky 2009-01-12 06:34:22 EST
The library routines package for NASL (the scripting language designed for the Nessus security scanner) incorrectly checked the result after
calling the DSA_do_verify function, allowing a malformed signature
to be treated as a good signature rather than as an error.  This issue
affected the signature checks on DSA keys used with SSL/TLS.

Relevant part of the code (nasl/nasl_crypto2.c):
647   if (DSA_do_verify((unsigned char*)data, datalen, sig, dsa))
648      retc->x.i_val = 1;

Proposed patch:
- if (DSA_do_verify((unsigned char*)data, datalen, sig, dsa))
+ if (DSA_do_verify((unsigned char*)data, datalen, sig, dsa) == 1)


This issue is related with recent OpenSSL's CVE-2008-5077 flaw.
Comment 1 Jan Lieskovsky 2009-01-12 06:35:13 EST
This issue affects all versions of the libnasl package, as shipped
with Fedora releases of 9, 10 and devel.

Please fix.
Comment 2 Jan Lieskovsky 2009-01-16 09:11:51 EST
Common Vulnerabilities and Exposures assigned an identifier CVE-2009-0125 to
the following vulnerability:

nasl/nasl_crypto2.c in the Nessus Attack Scripting Language library
(aka libnasl) 2.2.11 does not properly check the return value from the
OpenSSL DSA_do_verify function, which allows remote attackers to
bypass validation of the certificate chain via a malformed SSL/TLS
signature, a similar vulnerability to CVE-2008-5077.

Comment 3 Tomas Hoger 2009-01-22 03:33:35 EST
Nessus upstream authors disputed this as a security issue:

So while this is a bug, it's not considered security issue upstream.
Comment 4 Fedora Update System 2009-01-23 21:37:58 EST
libnasl-2.2.11-3.fc10, nessus-core-2.2.11-1.fc10, nessus-libraries-2.2.11-1.fc10 has been pushed to the Fedora 10 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 5 Fedora Update System 2009-01-23 21:41:13 EST
libnasl-2.2.11-3.fc9, nessus-core-2.2.11-1.fc9, nessus-libraries-2.2.11-1.fc9 has been pushed to the Fedora 9 stable repository.  If problems still persist, please make note of it in this bug report.

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