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ASN.1 parsing errors exist in implementations of SSL, TLS, S/MIME, PKCS#7 routines

Vulnerability Note VU#748355

Original Release Date: 2002-07-30 | Last Revised: 2002-09-30

Overview

Abstract Syntax Notation number One (ASN.1) is an international standard used to describe and transmit data packets between applications and across networks. There is a vulnerability related to ASN.1 that could permit an attacker to cause a denial of service or potentially execute arbitrary code.

Description

The ASN.1 library used by OpenSSL has several parsing errors which allow malformed certificate encodings to be parsed incorrectly. Attackers can exploit this vulnerability remotely to cause a denial of service or potentially execute arbitrary code, depending on the circumstance under which the vulnerable parser is exercised. Routines affected include those supporting SSL and TLS applications, as well as S/MIME (PKCS#7) and certificate creation.

Specifically, the parser implemented in various ASN.1 libraries accepts certain invalidly encoded data (in this case with an invalid length parameter) leading to improper interpretation of the data. This leads to undefined behavior which may lead to other security-related impacts (data executed as code, service termination, disclosure of sensitive information).

Impact

Attackers can exploit this vulnerability remotely to cause a variety of impacts, including denial of service, arbitrary code execution, and disclosure of sensitive information.

Solution

Apply the patches made available by your vendor, or upgrade to the recommended version. The "Systems Affected" section contains a list of vendors and details about the status of their products. Clicking on the vendor name will provide you with any statements that the vendor has made.

The OpenSSL team has recently released OpenSSL 0.9.6g to completely remove all known instances of this vulnerability.

Vendor Information

748355
 

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References

Acknowledgements

This vulnerability was independently discovered by Adi Stav and James Yonan. Our thanks to Stephen Henson for reporting on this vulnerability.

This document was written by Jason A Rafail and Jeffrey S. Havrilla.

Other Information

CVE IDs: CVE-2002-0659
CERT Advisory: CA-2002-23
Severity Metric: 31.33
Date Public: 2002-07-30
Date First Published: 2002-07-30
Date Last Updated: 2002-09-30 20:52 UTC
Document Revision: 33

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