Out-of-Bounds SNYK-DEBIAN8-PCRE3-345432

Introduction

In this article, we will discuss the out-of-bounds SNYK-DEBIAN8-PCRE3-345432 vulnerability, which affects PCRE 8.40 and PCRE2 10.23. This vulnerability allows remote attackers to cause a denial of service (segmentation violation for read access, and application crash) by triggering an invalid Unicode property lookup.

What is PCRE?

PCRE (Perl Compatible Regular Expressions) is a library that provides support for regular expressions in C. It is widely used in many applications, including web servers, email clients, and text editors. PCRE is a powerful tool for matching and manipulating text, but it can also be vulnerable to security exploits if not properly configured.

The Vulnerability

The out-of-bounds SNYK-DEBIAN8-PCRE3-345432 vulnerability affects PCRE 8.40 and PCRE2 10.23. It allows remote attackers to cause a denial of service (segmentation violation for read access, and application crash) by triggering an invalid Unicode property lookup. This vulnerability is caused by a bug in the PCRE library that allows an attacker to access memory outside the bounds of a buffer.

How Does the Vulnerability Work?

The vulnerability works by exploiting a bug in the PCRE library that allows an attacker to access memory outside the bounds of a buffer. When a regular expression is compiled, the PCRE library creates a buffer to store the compiled pattern. However, if the attacker can manipulate the buffer to point to a location outside the bounds of the buffer, they can access memory that is not allocated to the buffer. This can cause a segmentation fault, which can crash the application.

How to Fix the Vulnerability

Unfortunately, there is no fixed version of PCRE 8.40 and PCRE2 10.23 that is available for Debian 8. However, there are some workarounds that can be used to mitigate the vulnerability.

• Upgrade to a newer version of PCRE: If possible, upgrade to a newer version of PCRE that is not affected by this vulnerability.
• Use a different regular expression library: Consider using a different regular expression library that is not affected by this vulnerability.
• Disable Unicode property lookup: Disable Unicode property lookup in the PCRE library to prevent the vulnerability from being exploited.

References

• https://security-tracker.debian.org/tracker/CVE-2017-7186
• https://bugs.exim.org/show_bug.cgi?id=2052
• https://vcs.pcre.org/pcre2/code/trunk/src/pcre2_internal.h?r1=600&r2=670&sortby=date
• https://vcs.pcre.org/pcre2/code/trunk/src/p2_ucd.c?r1=316&r2=670&sortby=date
• https://vcs.pcre.org/pcre/code/trunk/pcre_internal.h?r1=1649&r2=1688&sortby=date
• https://vcs.pcre.org/pcre/code/trunk/pcre_ucd.c?r1=1490&r2=1688&sortby=date
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7186
• https://security.gentoo.org/glsa/201710-09
• https://security.gentoo.org/glsa/201710-25
• https://blogs.gentoo.org/ago/2017/03/14/libpcre-invalid-memory-read-in-match-pcre_exec-c/
• https://access.redhat.com/errata/RHSA-2018:2486
• http://www.securityfocus.com/bid/97030
• http://people.ubuntu.com/~ubuntu-security/cve/CVE-2017-7186

Conclusion

Q: What is the out-of-bounds SNYK-DEBIAN8-PCRE3-345432 vulnerability?

A: The out-of-bounds SNYK-DEBIAN8-PCRE3-345432 vulnerability is a critical vulnerability in PCRE 8.40 and PCRE2 10.23 that allows remote attackers to cause a denial of service (segmentation violation for read access, and application crash) by triggering an invalid Unicode property lookup.

Q: What is PCRE?

A: PCRE (Perl Compatible Regular Expressions) is a library that provides support for regular expressions in C. It is widely used in many applications, including web servers, email clients, and text editors.

Q: How does the vulnerability work?

A: The vulnerability works by exploiting a bug in the PCRE library that allows an attacker to access memory outside the bounds of a buffer. When a regular expression is compiled, the PCRE library creates a buffer to store the compiled pattern. However, if the attacker can manipulate the buffer to point to a location outside the bounds of the buffer, they can access memory that is not allocated to the buffer. This can cause a segmentation fault, which can crash the application.

Q: What are the consequences of the vulnerability?

A: The consequences of the vulnerability are a denial of service (segmentation violation for read access, and application crash) by triggering an invalid Unicode property lookup. This can cause the application to crash, and potentially allow an attacker to execute arbitrary code.

Q: How can I prevent the vulnerability from being exploited?

A: To prevent the vulnerability from being exploited, you can:

• Upgrade to a newer version of PCRE: If possible, upgrade to a newer version of PCRE that is not affected by this vulnerability.
• Use a different regular expression library: Consider using a different regular expression library that is not affected by this vulnerability.
• Disable Unicode property lookup: Disable Unicode property lookup in the PCRE library to prevent the vulnerability from being exploited.

Q: Is there a fixed version of PCRE 8.40 and PCRE2 10.23 available for Debian 8?

A: Unfortunately, there is no fixed version of PCRE 8.40 and PCRE2 10.23 that is available for Debian 8.

Q: What are the references for this vulnerability?

A: The references for this vulnerability are:

• https://security-tracker.debian.org/tracker/CVE-2017-7186
• https://bugs.exim.org/show_bug.cgi?id=2052
• https://vcs.pcre.org/pcre2/code/trunk/src/pcre2_internal.h?r1=600&r2=670&sortby=date
• https://vcs.pcre.org/pcre2/code/trunk/src/pcre2_ucd.c?r1=316&r2=670&sortby=date
• https://vcs.pcre.org/pcre/code/trunk/pcre_internal.h?r1=1649&r2=1688&sortby=date
• https://vcs.pcre.org/pcre/code/trunk/pcre_ucd.c?r1=1490&r2=1688&sortby=date
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7186
• https://security.gentoo.org/glsa/201710-09
• https://security.gentoo.org/glsa/201710-25
• https://blogs.gentoo.org/ago/2017/03/14/libpcre-invalid-memory-read-in-match-pcre_exec-c/
• https://access.redhat.com/errata/RHSA-2018:2486
• http://www.securityfocus.com/bid/97030
• http://people.ubuntu.com/~ubuntu-security/cve/CVE-2017-7186

Conclusion

In conclusion, the out-of-bounds SNYK-DEBIAN8-PCRE3-345432 vulnerability is a critical vulnerability in PCRE 8.40 and PCRE2 10.23 that allows remote attackers to cause a denial of service (segmentation violation for read access, and application crash) by triggering an invalid Unicode property lookup. It is essential to upgrade to a newer version of PCRE or use a different regular expression library to prevent the vulnerability from being exploited.