294 lines
12 KiB
Markdown
294 lines
12 KiB
Markdown
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# curl vulnerability disclosure policy
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This document describes how security vulnerabilities are handled in the curl
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project.
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## Publishing Information
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All known and public curl or libcurl related vulnerabilities are listed on
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[the curl website security page](https://curl.se/docs/security.html).
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Security vulnerabilities **should not** be entered in the project's public bug
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tracker.
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## Vulnerability Handling
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The typical process for handling a new security vulnerability is as follows.
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No information should be made public about a vulnerability until it is
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formally announced at the end of this process. That means, for example, that a
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bug tracker entry must NOT be created to track the issue since that will make
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the issue public and it should not be discussed on any of the project's public
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mailing lists. Messages associated with any commits should not make any
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reference to the security nature of the commit if done prior to the public
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announcement.
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- The person discovering the issue, the reporter, reports the vulnerability on
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[HackerOne](https://hackerone.com/curl). Issues filed there reach a handful
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of selected and trusted people.
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- Messages that do not relate to the reporting or managing of an undisclosed
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security vulnerability in curl or libcurl are ignored and no further action
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is required.
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- A person in the security team responds to the original report to acknowledge
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that a human has seen the report.
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- The security team investigates the report and either rejects it or accepts
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it. See below for examples of problems that are not considered
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vulnerabilities.
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- If the report is rejected, the team writes to the reporter to explain why.
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- If the report is accepted, the team writes to the reporter to let them
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know it is accepted and that they are working on a fix.
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- The security team discusses the problem, works out a fix, considers the
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impact of the problem and suggests a release schedule. This discussion
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should involve the reporter as much as possible.
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- The release of the information should be "as soon as possible" and is most
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often synchronized with an upcoming release that contains the fix. If the
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reporter, or anyone else involved, thinks the next planned release is too
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far away, then a separate earlier release should be considered.
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- Write a security advisory draft about the problem that explains what the
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problem is, its impact, which versions it affects, solutions or workarounds,
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when the release is out and make sure to credit all contributors properly.
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Figure out the CWE (Common Weakness Enumeration) number for the flaw. See
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[SECURITY-ADVISORY](https://curl.se/dev/advisory.html) for help on creating
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the advisory.
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- Request a CVE number from HackerOne
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- Update the "security advisory" with the CVE number.
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- The security team commits the fix in a private branch. The commit message
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should ideally contain the CVE number. If the severity level of the issue is
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set to Low or Medium, the fix is allowed to get merged into the master
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repository via a normal PR - but without mentioning it being a security
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vulnerability.
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- The monetary reward part of the bug-bounty is managed by the Internet Bug
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Bounty team and the reporter is asked to request the reward from them after
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the issue has been completely handled and published by curl.
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- No more than 10 days before release, inform
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[distros@openwall](https://oss-security.openwall.org/wiki/mailing-lists/distros)
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to prepare them about the upcoming public security vulnerability
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announcement - attach the advisory draft for information with CVE and
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current patch. 'distros' does not accept an embargo longer than 14 days and
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they do not care for Windows-specific flaws.
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- No more than 48 hours before the release, the private branch is merged into
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the master branch and pushed. Once pushed, the information is accessible to
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the public and the actual release should follow suit immediately afterwards.
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The time between the push and the release is used for final tests and
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reviews.
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- The project team creates a release that includes the fix.
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- The project team announces the release and the vulnerability to the world in
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the same manner we always announce releases. It gets sent to the
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curl-announce, curl-library and curl-users mailing lists.
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- The security web page on the website should get the new vulnerability
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mentioned.
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## security (at curl dot se)
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This is a private mailing list for discussions on and about curl security
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issues.
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Who is on this list? There are a couple of criteria you must meet, and then we
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might ask you to join the list or you can ask to join it. It really is not a
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formal process. We basically only require that you have a long-term presence
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in the curl project and you have shown an understanding for the project and
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its way of working. You must have been around for a good while and you should
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have no plans of vanishing in the near future.
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We do not make the list of participants public mostly because it tends to vary
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somewhat over time and a list somewhere will only risk getting outdated.
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## Publishing Security Advisories
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1. Write up the security advisory, using markdown syntax. Use the same
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subtitles as last time to maintain consistency.
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2. Name the advisory file after the allocated CVE id.
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3. Add a line on the top of the array in `curl-www/docs/vuln.pm`.
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4. Put the new advisory markdown file in the `curl-www/docs/` directory. Add it
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to the git repository.
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5. Run `make` in your local web checkout and verify that things look fine.
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6. On security advisory release day, push the changes on the curl-www
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repository's remote master branch.
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## HackerOne
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Request the issue to be disclosed. If there are sensitive details present in
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the report and discussion, those should be redacted from the disclosure. The
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default policy is to disclose as much as possible as soon as the vulnerability
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has been published.
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## Bug Bounty
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See [BUG-BOUNTY](https://curl.se/docs/bugbounty.html) for details on the
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bug bounty program.
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# Severity levels
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The curl project's security team rates security problems using four severity
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levels depending how serious we consider the problem to be. We use **Low**,
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**Medium**, **High** and **Critical**. We refrain from using numerical scoring
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of vulnerabilities.
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When deciding severity level on a particular issue, we take all the factors
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into account: attack vector, attack complexity, required privileges, necessary
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build configuration, protocols involved, platform specifics and also what
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effects a possible exploit or trigger of the issue can lead do, including
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confidentiality, integrity or availability problems.
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## Low
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This is a security problem that is truly hard or unlikely to exploit or
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trigger. Due to timing, platform requirements or the fact that options or
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protocols involved are rare etc. [Past
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example](https://curl.se/docs/CVE-2022-43552.html)
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## Medium
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This is a security problem that is less hard than **Low** to exploit or
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trigger. Less strict timing, wider platforms availability or involving more
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widely used options or protocols. A problem that usually needs something else
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to also happen to become serious. [Past
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example](https://curl.se/docs/CVE-2022-32206.html)
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## High
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This issue in itself a serious problem with real world impact. Flaws that can
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easily compromise the confidentiality, integrity or availability of resources.
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Exploiting or triggering this problem is not hard. [Past
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example](https://curl.se/docs/CVE-2019-3822.html)
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## Critical
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Easily exploitable by a remote unauthenticated attacker and lead to system
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compromise (arbitrary code execution) without requiring user interaction, with
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a common configuration on a popular platform. This issue has few restrictions
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and requirements and can be exploited easily using most curl configurations.
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[Past example](https://curl.se/docs/CVE-2000-0973.html)
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# Not security issues
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This is an incomplete list of issues that are not considered vulnerabilities.
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## Small memory leaks
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We do not consider a small memory leak a security problem; even if the amount
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of allocated memory grows by a small amount every now and then. Long-living
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applications and services already need to have counter-measures and deal with
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growing memory usage, be it leaks or just increased use. A small memory or
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resource leak is then expected to *not* cause a security problem.
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Of course there can be a discussion if a leak is small or not. A large leak
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can be considered a security problem due to the DOS risk. If leaked memory
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contains sensitive data it might also qualify as a security problem.
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## Never-ending transfers
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We do not consider flaws that cause a transfer to never end to be a security
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problem. There are already several benign and likely reasons for transfers to
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stall and never end, so applications that cannot deal with never-ending
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transfers already need to have counter-measures established.
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If the problem avoids the regular counter-measures when it causes a never-
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ending transfer, it might be a security problem.
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## Not practically possible
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If the flaw or vulnerability cannot practically get executed on existing
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hardware it is not a security problem.
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## API misuse
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If a reported issue only triggers by an application using the API in a way
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that is not documented to work or even documented to not work, it is probably
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not going to be considered a security problem. We only guarantee secure and
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proper functionality when the APIs are used as expected and documented.
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There can be a discussion about what the documentation actually means and how
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to interpret the text, which might end up with us still agreeing that it is a
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security problem.
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## Local attackers already present
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When an issue can only be attacked or misused by an attacker present on the
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local system or network, the bar is raised. If a local user wrongfully has
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elevated rights on your system enough to attack curl, they can probably
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already do much worse harm and the problem is not really in curl.
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## Experiments
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Vulnerabilities in features which are off by default (in the build) and
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documented as experimental, are not eligible for a reward and we do not
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consider them security problems.
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## URL inconsistencies
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URL parser inconsistencies between browsers and curl are expected and are not
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considered security vulnerabilities. The WHATWG URL Specification and RFC
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3986+ (the plus meaning that it is an extended version) [are not completely
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interoperable](https://github.com/bagder/docs/blob/master/URL-interop.md).
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Obvious parser bugs can still be vulnerabilities of course.
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## Visible command line arguments
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The curl command blanks the contents of a number of command line arguments to
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prevent them from appearing in process listings. It does not blank all
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arguments even if some of them that are not blanked might contain sensitive
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data. We consider this functionality a best-effort and omissions are not
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security vulnerabilities.
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- not all systems allow the arguments to be blanked in the first place
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- since curl blanks the argument itself they will be readable for a short
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moment no matter what
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- virtually every argument can contain sensitive data, depending on use
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- blanking all arguments would make it impractical for users to differentiate
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curl command lines in process listings
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## Busy-loops
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Busy-loops that consume 100% CPU time but eventually end (perhaps due to a set
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timeout value or otherwise) are not considered security problems. Applications
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are supposed to already handle situations when the transfer loop legitimately
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consumes 100% CPU time, so while a prolonged such busy-loop is a nasty bug, we
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do not consider it a security problem.
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## Saving files
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curl cannot protect against attacks where an attacker has write access to the
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same directory where curl is directed to save files.
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## Tricking a user to run a command line
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A creative, misleading or funny looking command line is not a security
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problem. The curl command line tool takes options and URLs on the command line
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and if an attacker can trick the user to run a specifically crafted curl
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command line, all bets are off. Such an attacker can just as well have the
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user run a much worse command that can do something fatal (like
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`sudo rm -rf /`).
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## Terminal output and escape sequences
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Content that is transferred from a server and gets displayed in a terminal by
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curl may contain escape sequences or use other tricks to fool the user. This
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is curl working as designed and is not a curl security problem. Escape
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sequences, moving cursor, changing color etc, is also frequently used for
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good. To reduce the risk of getting fooled, save files and browse them after
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download using a display method that minimizes risks.
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