PERLSECPOLICY(1) Perl Programmers Reference Guide PERLSECPOLICY(1)
NAME
perlsecpolicy - Perl security report handling policy
DESCRIPTION
The Perl project takes security issues seriously.
The responsibility for handling security reports in a timely and
effective manner has been delegated to a security team composed of a
subset of the Perl core developers.
This document describes how the Perl security team operates and how the
team evaluates new security reports.
REPORTING SECURITY ISSUES IN PERL
If you believe you have found a security vulnerability in the Perl
interpreter or modules maintained in the core Perl codebase, email the
details to perl-security@perl.org <mailto:perl-security@perl.org>. This
address is a closed membership mailing list monitored by the Perl
security team.
You should receive an initial response to your report within 72 hours.
If you do not receive a response in that time, please contact the Perl
Steering Council <mailto:steering-council@perl.org>.
When members of the security team reply to your messages, they will
generally include the perl-security@perl.org address in the "To" or "CC"
fields of the response. This allows all of the security team to follow
the discussion and chime in as needed. Use the "Reply-all" functionality
of your email client when you send subsequent responses so that the
entire security team receives the message.
The security team will evaluate your report and make an initial
determination of whether it is likely to fit the scope of issues the
team handles. General guidelines about how this is determined are
detailed in the "WHAT ARE SECURITY ISSUES" section.
If your report meets the team's criteria, an issue will be opened in the
team's private issue tracker and you will be provided the issue's ID
number. Issue identifiers have the form perl-security#NNN. Include this
identifier with any subsequent messages you send.
The security team will send periodic updates about the status of your
issue and guide you through any further action that is required to
complete the vulnerability remediation process. The stages
vulnerabilities typically go through are explained in the "HOW WE DEAL
WITH SECURITY ISSUES" section.
WHAT ARE SECURITY ISSUES
A vulnerability is a behavior of a software system that compromises the
system's expected confidentiality, integrity or availability
protections.
A security issue is a bug in one or more specific components of a
software system that creates a vulnerability.
Software written in the Perl programming language is typically composed
of many layers of software written by many different groups. It can be
very complicated to determine which specific layer of a complex real-
world application was responsible for preventing a vulnerable behavior,
but this is an essential part of fixing the vulnerability.
Software covered by the Perl security team
The Perl security team handles security issues in:
• The Perl interpreter
• The Perl modules shipped with the interpreter that are developed in
the core Perl repository
• The command line tools shipped with the interpreter that are
developed in the core Perl repository
Files under the cpan/ directory in Perl's repository and release
tarballs are developed and maintained independently. The Perl security
team does not directly handle security issues for these modules, but
since this code is bundled with Perl, we will assist in forwarding the
issue to the relevant maintainer(s) and you can still report these
issues to us in secrecy.
Bugs that may qualify as security issues in Perl
Perl is designed to be a fast and flexible general purpose programming
language. The Perl interpreter and Perl modules make writing safe and
secure applications easy, but they do have limitations.
As a general rule, a bug in Perl needs to meet all of the following
criteria to be considered a security issue:
• The vulnerable behavior is not mentioned in Perl's documentation or
public issue tracker.
• The vulnerable behavior is not implied by an expected behavior.
• The vulnerable behavior is not a generally accepted limitation of
the implementation.
• The vulnerable behavior is likely to be exposed to attack in
otherwise secure applications written in Perl.
• The vulnerable behavior provides a specific tangible benefit to an
attacker that triggers the behavior.
Bugs that do not qualify as security issues in Perl
There are certain categories of bugs that are frequently reported to the
security team that do not meet the criteria listed above.
The following is a list of commonly reported bugs that are not handled
as security issues.
Feeding untrusted code to the interpreter
The Perl parser is not designed to evaluate untrusted code. If your
application requires the evaluation of untrusted code, it should rely on
an operating system level sandbox for its security.
Stack overflows due to excessive recursion
Excessive recursion is often caused by code that does not enforce limits
on inputs. The Perl interpreter assumes limits on recursion will be
enforced by the application.
Out of memory errors
Common Perl constructs such as "pack", the "x" operator, and regular
expressions accept numeric quantifiers that control how much memory will
be allocated to store intermediate values or results. If you allow an
attacker to supply these quantifiers and consume all available memory,
the Perl interpreter will not prevent it.
Escape from a Safe compartment
Opcode restrictions and Safe compartments are not supported as security
mechanisms. The Perl parser is not designed to evaluate untrusted code.
Use of the "p" and "P" pack templates
These templates are unsafe by design.
Stack not reference-counted issues
These bugs typically present as use-after-free errors or as assertion
failures on the type of a "SV". Stack not reference-counted crashes
usually occur because code is both modifying a reference or glob and
using the values referenced by that glob or reference.
This type of bug is a long standing issue with the Perl interpreter that
seldom occurs in normal code. Examples of this type of bug generally
assume that attacker-supplied code will be evaluated by the Perl
interpreter.
Thawing attacker-supplied data with Storable
Storable is designed to be a very fast serialization format. It is not
designed to be safe for deserializing untrusted inputs.
Using attacker supplied SDBM_File databases
The SDBM_File module is not intended for use with untrusted SDBM
databases.
Badly encoded UTF-8 flagged scalars
This type of bug occurs when the ":utf8" PerlIO layer is used to read
badly encoded data, or other mechanisms are used to directly manipulate
the UTF-8 flag on an SV.
A badly encoded UTF-8 flagged SV is not a valid SV. Code that creates
SV's in this fashion is corrupting Perl's internal state.
Issues that exist only in blead, or in a release candidate
The blead branch and Perl release candidates do not receive security
support. Security defects that are present only in pre-release versions
of Perl are handled through the normal bug reporting and resolution
process.
CPAN modules or other Perl project resources
The Perl security team is focused on the Perl interpreter and modules
maintained in the core Perl codebase. The team has no special access to
fix CPAN modules, applications written in Perl, Perl project websites,
Perl mailing lists or the Perl IRC servers.
Emulated POSIX behaviors on Windows systems
The Perl interpreter attempts to emulate "fork", "system", "exec" and
other POSIX behaviors on Windows systems. This emulation has many quirks
that are extensively documented in Perl's public issue tracker.
Changing these behaviors would cause significant disruption for existing
users on Windows.
Bugs that require special categorization
Some bugs in the Perl interpreter occur in areas of the codebase that
are both security sensitive and prone to failure during normal usage.
Regular expressions
Untrusted regular expressions are generally safe to compile and match
against with several caveats. The following behaviors of Perl's regular
expression engine are the developer's responsibility to constrain.
The evaluation of untrusted regular expressions while "use re 'eval';"
is in effect is never safe.
Regular expressions are not guaranteed to compile or evaluate in any
specific finite time frame.
Regular expressions may consume all available system memory when they
are compiled or evaluated.
Regular expressions may cause excessive recursion that halts the perl
interpreter.
As a general rule, do not expect Perl's regular expression engine to be
resistant to denial of service attacks.
DB_File, ODBM_File, or GDBM_File databases
These modules rely on external libraries to interact with database
files.
Bugs caused by reading and writing these file formats are generally
caused by the underlying library implementation and are not security
issues in Perl.
Bugs where Perl mishandles unexpected valid return values from the
underlying libraries may qualify as security issues in Perl.
Algorithmic complexity attacks
The perl interpreter is reasonably robust to algorithmic complexity
attacks. It is not immune to them.
Algorithmic complexity bugs that depend on the interpreter processing
extremely large amounts of attacker supplied data are not generally
handled as security issues.
See "Algorithmic Complexity Attacks" in perlsec for additional
information.
HOW WE DEAL WITH SECURITY ISSUES
The Perl security team follows responsible disclosure practices.
Security issues are kept secret until a fix is readily available for
most users. This minimizes inherent risks users face from
vulnerabilities in Perl.
Hiding problems from the users temporarily is a necessary trade-off to
keep them safe. Hiding problems from users permanently is not the goal.
When you report a security issue privately to the perl-security@perl.org
<mailto:perl-security@perl.org> contact address, we normally expect you
to follow responsible disclosure practices in the handling of the
report. If you are unable or unwilling to keep the issue secret until a
fix is available to users you should state this clearly in the initial
report.
The security team's vulnerability remediation workflow is intended to be
as open and transparent as possible about the state of your security
report.
Perl's vulnerability remediation workflow
Initial contact
New vulnerability reports will receive an initial reply within 72 hours
from the time they arrive at the security team's mailing list. If you do
not receive any response in that time, contact the Perl Steering Council
<mailto:steering-council@perl.org>.
The initial response sent by the security team will confirm your message
was received and provide an estimated time frame for the security team's
triage analysis.
Initial triage
The security team will evaluate the report and determine whether or not
it is likely to meet the criteria for handling as a security issue.
The security team aims to complete the initial report triage within two
weeks' time. Complex issues that require significant discussion or
research may take longer.
If the security report cannot be reproduced or does not meet the team's
criteria for handling as a security issue, you will be notified by email
and given an opportunity to respond.
Issue ID assignment
Security reports that pass initial triage analysis are turned into
issues in the security team's private issue tracker. When a report
progresses to this point you will be provided the issue ID for future
reference. These identifiers have the format perl-security#NNN or
Perl/perl-security#NNN.
The assignment of an issue ID does not confirm that a security report
represents a vulnerability in Perl. Many reports require further
analysis to reach that determination.
Issues in the security team's private tracker are used to collect
details about the problem and track progress towards a resolution. These
notes and other details are not made public when the issue is resolved.
Keeping the issue notes private allows the security team to freely
discuss attack methods, attack tools, and other related private issues.
Development of patches
Members of the security team will inspect the report and related code in
detail to produce fixes for supported versions of Perl.
If the team discovers that the reported issue does not meet the team's
criteria at this stage, you will be notified by email and given an
opportunity to respond before the issue is closed.
The team may discuss potential fixes with you or provide you with
patches for testing purposes during this time frame. No information
should be shared publicly at this stage.
CVE ID assignment
Once an issue is fully confirmed and a potential fix has been found, the
security team will request a CVE identifier for the issue to use in
public announcements.
Details like the range of vulnerable Perl versions and identities of the
people that discovered the flaw need to be collected to submit the CVE
ID request.
The security team may ask you to clarify the exact name we should use
when crediting discovery of the issue. The "Vulnerability credit and
bounties" section of this document explains our preferred format for
this credit.
Once a CVE ID has been assigned, you will be notified by email. The
vulnerability should not be discussed publicly at this stage.
Pre-release notifications
When the security team is satisfied that the fix for a security issue is
ready to release publicly, a pre-release notification announcement is
sent to the major redistributors of Perl.
This pre-release announcement includes a list of Perl versions that are
affected by the flaw, an analysis of the risks to users, patches the
security team has produced, and any information about mitigations or
backporting fixes to older versions of Perl that the security team has
available.
The pre-release announcement will include a specific target date when
the issue will be announced publicly. The time frame between the pre-
release announcement and the release date allows redistributors to
prepare and test their own updates and announcements. During this period
the vulnerability details and fixes are embargoed and should not be
shared publicly. This embargo period may be extended further if problems
are discovered during testing.
You will be sent the portions of pre-release announcements that are
relevant to the specific issue you reported. This email will include the
target release date. Additional updates will be sent if the target
release date changes.
Pre-release testing
The Perl security team does not directly produce official Perl releases.
The team releases security fixes by placing commits in Perl's public git
repository and sending announcements.
Many users and redistributors prefer using official Perl releases rather
than applying patches to an older release. The security team works with
Perl's release managers to make this possible.
New official releases of Perl are generally produced and tested on
private systems during the pre-release embargo period.
Release of fixes and announcements
At the end of the embargo period the security fixes will be committed to
Perl's public git repository and announcements will be sent to the
perl5-porters <https://lists.perl.org/list/perl5-porters.html> and oss-
security <https://oss-security.openwall.org/wiki/mailing-lists/oss-
security> mailing lists.
If official Perl releases are ready, they will be published at this time
and announced on the perl5-porters
<https://lists.perl.org/list/perl5-porters.html> mailing list.
The security team will send a follow-up notification to everyone that
participated in the pre-release embargo period once the release process
is finished. Vulnerability reporters and Perl redistributors should not
publish their own announcements or fixes until the Perl security team's
release process is complete.
Publicly known and zero-day security issues
The security team's vulnerability remediation workflow assumes that
issues are reported privately and kept secret until they are resolved.
This isn't always the case and information occasionally leaks out before
a fix is ready.
In these situations the team must decide whether operating in secret
increases or decreases the risk to users of Perl. In some cases being
open about the risk a security issue creates will allow users to defend
against it, in other cases calling attention to an unresolved security
issue will make it more likely to be misused.
Zero-day security issues
If an unresolved critical security issue in Perl is being actively
abused to attack systems the security team will send out announcements
as rapidly as possible with any mitigations the team has available.
Perl's public defect tracker will be used to handle the issue so that
additional information, fixes, and CVE IDs are visible to affected users
as rapidly as possible.
Other leaks of security issue information
Depending on the prominence of the information revealed about a security
issue and the issue's risk of becoming a zero-day attack, the security
team may skip all or part of its normal remediation workflow.
If the security team learns of a significant security issue after it has
been identified and resolved in Perl's public issue tracker, the team
will request a CVE ID and send an announcement to inform users.
Vulnerability credit and bounties
The Perl project appreciates the effort security researchers invest in
making Perl safe and secure.
Since much of this work is hidden from the public, crediting researchers
publicly is an important part of the vulnerability remediation process.
Credits in vulnerability announcements
When security issues are fixed we will attempt to credit the specific
researcher(s) that discovered the flaw in our announcements.
Credits are announced using the researcher's preferred full name.
If the researcher's contributions were funded by a specific company or
part of an organized vulnerability research project, we will include a
short name for this group at the researcher's request.
Perl's announcements are written in the English language using the 7bit
ASCII character set to be reproducible in a variety of formats. We do
not include hyperlinks, domain names or marketing material with these
acknowledgments.
In the event that proper credit for vulnerability discovery cannot be
established or there is a disagreement between the Perl security team
and the researcher about how the credit should be given, it will be
omitted from announcements.
Bounties for Perl vulnerabilities
The Perl project is a non-profit volunteer effort. We do not provide any
monetary rewards for reporting security issues in Perl.
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