# bug classification discussion - Thread: https://externals.io/message/96574 - Original archive: https://news-web.php.net/php.internals/96574 - Started by Stanislav Malyshev on 2016-10-24T05:23:06+00:00 - Messages: 18 - Reply by email to internals@lists.php.net - More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt --- ## #96574 — Stanislav Malyshev — 2016-10-24T05:23:06+00:00 URL: https://externals.io/message/96574#96574 Hi! We have had a bunch of bugs recently which are essentially one and the same issue: PHP 5.6 allows only int-sized strings, but many functions don't check the size of the string they produce. This can lead to int overflows inside php and also can break other libraries that also assume string sizes are ints and this can cause all kinds of weirdness. However, these bugs are very unlikely to manifest in production setting for one simple reason - they require PHP to run with no memory limit, and I haven't seen many setups that run with no memory limit. I'm not going to go into specifics here, since some of the issues are still not fixed, but you can talk to me privately if you need examples or browse changelogs of later 5.6 releases. A twin brother of this is in 7.0 where there are just integer overflows in string size calculations. Usually that requires huge strings as inputs, so also requires running with no memory limit. These bugs are now treated as security issues, due to the fact that in theory somebody might be running with no memory limit and get huge string as an input from user. However, it was questioned that we indeed should treat them so, due to the fact that encountering them in production is unlikely, and due to the fact that they require patching in many places, and merging those fixes out-of-band creates significant potential for bugs. I'd like to hear feedback on this, especially - though definitely not only! - from RMs and distro people. There are some libraries (ICU, I'm looking at you!) which have much lower limits and fixed buffers inside and unfortunately they don't enforce or check those limits, they just kind of assume everybody is nice. For those, I think we'd have to treat issues stemming from that as security issues if they look exploitable. Also, some libraries have int overflows independent of PHP (also needing huge strings to trigger) - not sure what to do with those. Would be glad to hear some discussion on this. -- Stas Malyshev smalyshev@gmail.com --- ## #96592 — Anatol Belski — 2016-10-24T13:44:48+00:00 URL: https://externals.io/message/96574#96592 · In reply to: #96574 Hi Stas, > -----Original Message----- > From: Stanislav Malyshev [mailto:smalyshev@gmail.com] > Sent: Monday, October 24, 2016 7:23 AM > To: PHP Internals > Cc: Remi Collet > Subject: [PHP-DEV] bug classification discussion > > Hi! > > We have had a bunch of bugs recently which are essentially one and the same > issue: PHP 5.6 allows only int-sized strings, but many functions don't check the > size of the string they produce. This can lead to int overflows inside php and also > can break other libraries that also assume string sizes are ints and this can cause > all kinds of weirdness. > However, these bugs are very unlikely to manifest in production setting for one > simple reason - they require PHP to run with no memory limit, and I haven't seen > many setups that run with no memory limit. I'm not going to go into specifics > here, since some of the issues are still not fixed, but you can talk to me privately > if you need examples or browse changelogs of later 5.6 releases. > > A twin brother of this is in 7.0 where there are just integer overflows in string > size calculations. Usually that requires huge strings as inputs, so also requires > running with no memory limit. > > These bugs are now treated as security issues, due to the fact that in theory > somebody might be running with no memory limit and get huge string as an > input from user. However, it was questioned that we indeed should treat them > so, due to the fact that encountering them in production is unlikely, and due to > the fact that they require patching in many places, and merging those fixes out- > of-band creates significant potential for bugs. > > I'd like to hear feedback on this, especially - though definitely not only! - from > RMs and distro people. > > There are some libraries (ICU, I'm looking at you!) which have much lower limits > and fixed buffers inside and unfortunately they don't enforce or check those > limits, they just kind of assume everybody is nice. For those, I think we'd have to > treat issues stemming from that as security issues if they look exploitable. Also, > some libraries have int overflows independent of PHP (also needing huge strings > to trigger) - not sure what to do with those. > > Would be glad to hear some discussion on this. Thanks for bringing this up. I was looking through several docs in this regard, and IMHO it'd be indeed useful to have just clear definitions of security bugs. It could be possible to create a document, which would guide both reporters and maintainers to consider the exact metrics. As an example of such a classification, I would like to link the document below, while there are also other classifications possible and we for sure need to develop our own that fits the situations we have in PHP best https://access.redhat.com/security/updates/classification While every case can of course have individual impacts, having a classification that covers some big part is IMO a clear way to go. For example, correlating the linked doc, with a bit modification: High - vulnerability, that can be exploited by unauthenticated remote users, despite the highest possible secure server settings and is caused by PHP's internal bug or a certain way the script is programmed . Such a vulnerability would cause a serious damage like an unauthorized root access, data loss, confidentiality compromise, etc. Moderate - vulnerability is hard to exploit and localized in some extension and doesn't affect any internal code in main, TSRM, Zend or mandatory extensions, but would still cause serious damages. Low - vulnerability is hard to exploit or requires insecure PHP or system configuration. It might make sense to start writing up such a document and extending it while having actual issues. Once we have such a definition, it could even go through an RFC and become a standard. This might indeed ease the equilibration between security and QA, thus to crystalize a better security issue handling process. IMHO, the security bugs with the low severity as from above, are fine to be merged already in RCs. Regards Anatol --- ## #96595 — Anatol Belski — 2016-10-24T14:02:10+00:00 URL: https://externals.io/message/96574#96595 · In reply to: #96574 > -----Original Message----- > From: Anatol Belski [mailto:anatol.php@belski.net] > Sent: Monday, October 24, 2016 3:45 PM > To: 'Stanislav Malyshev' ; 'PHP Internals' > > Cc: 'Remi Collet' > Subject: RE: [PHP-DEV] bug classification discussion > > Hi Stas, > > > […] > changelogs of later 5.6 releases. > > […] > potential for bugs. > > […] > sure what to do with those. > > […] > > Thanks for bringing this up. I was looking through several docs in this regard, and > IMHO it'd be indeed useful to have just clear definitions of security bugs. It could > be possible to create a document, which would guide both reporters and > maintainers to consider the exact metrics. As an example of such a classification, > I would like to link the document below, while there are also other > classifications possible and we for sure need to develop our own that fits the > situations we have in PHP best > > https://access.redhat.com/security/updates/classification > > While every case can of course have individual impacts, having a classification > that covers some big part is IMO a clear way to go. > > For example, correlating the linked doc, with a bit modification: > > High - vulnerability, that can be exploited by unauthenticated remote users, > despite the highest possible secure server settings and is caused by PHP's > internal bug or a certain way the script is programmed . Such a vulnerability > would cause a serious damage like an unauthorized root access, data loss, > confidentiality compromise, etc. > > Moderate - vulnerability is hard to exploit and localized in some extension and > doesn't affect any internal code in main, TSRM, Zend or mandatory extensions, > but would still cause serious damages. > > Low - vulnerability is hard to exploit or requires insecure PHP or system > configuration. > > It might make sense to start writing up such a document and extending it while > having actual issues. Once we have such a definition, it could even go through > an RFC and become a standard. This might indeed ease the equilibration > between security and QA, thus to crystalize a better security issue handling > process. IMHO, the security bugs with the low severity as from above, are fine > to be merged already in RCs. > Btw to low I'd add also - scripts that are coded insecure way (fe accepting direct _GET/_POST data) - bugs caused by the dependency libraries, unless in mandatory extensions or defined specifically otherwise - bugs caused by incorrect API usage in non core extensions (fe passing `NULL` to internal core function, that expects an allocated var) Regards Anatol --- ## #96631 — Remi Collet — 2016-10-28T09:18:19+00:00 URL: https://externals.io/message/96574#96631 · In reply to: #96574 Le 24/10/2016 à 07:23, Stanislav Malyshev a écrit : > Hi! > > We have had a bunch of bugs recently which are essentially one and the > same issue: PHP 5.6 allows only int-sized strings, but many functions > don't check the size of the string they produce. This can lead to int > overflows inside php and also can break other libraries that also assume > string sizes are ints and this can cause all kinds of weirdness. > However, these bugs are very unlikely to manifest in production setting > for one simple reason - they require PHP to run with no memory limit, > and I haven't seen many setups that run with no memory limit. I'm not > going to go into specifics here, since some of the issues are still not > fixed, but you can talk to me privately if you need examples or browse > changelogs of later 5.6 releases. > > A twin brother of this is in 7.0 where there are just integer overflows > in string size calculations. Usually that requires huge strings as > inputs, so also requires running with no memory limit. > > These bugs are now treated as security issues, My main concern is not to know if we treat this bugs as security or not. It is mainly about "classification", and I think "low" risk bugs should be fixed using the normal bug process (going in a RC versions) rather than a specific process (fixed only at GA time), which should be reserved for higher risk bugs. Remi --- ## #96632 — Joe Watkins — 2016-10-28T10:03:51+00:00 URL: https://externals.io/message/96574#96632 · In reply to: #96631 Morning, Trying to re-shape our own classification system seems like a good idea. I have no good idea of how to write such a document, would be happy to review (and make other people review) if someone were to start. Cheers Joe On Fri, Oct 28, 2016 at 10:18 AM, Remi Collet wrote: > Le 24/10/2016 à 07:23, Stanislav Malyshev a écrit : > > […] > > My main concern is not to know if we treat this bugs as security or not. > > It is mainly about "classification", and I think "low" risk bugs should > be fixed using the normal bug process (going in a RC versions) rather > than a specific process (fixed only at GA time), which should be > reserved for higher risk bugs. > > > Remi --- ## #96635 — Ferenc Kovacs — 2016-10-28T15:33:23+00:00 URL: https://externals.io/message/96574#96635 · In reply to: #96631 On Fri, Oct 28, 2016 at 11:18 AM, Remi Collet wrote: > Le 24/10/2016 à 07:23, Stanislav Malyshev a écrit : > > […] > > My main concern is not to know if we treat this bugs as security or not. > > It is mainly about "classification", and I think "low" risk bugs should > be fixed using the normal bug process (going in a RC versions) rather > than a specific process (fixed only at GA time), which should be > reserved for higher risk bugs. > > > Remi > > > I agree with Remi, these should be fixed via the normal development process so we can catch any issues during the RC. These are basically the same issue, they can be exploited the same way (which I agree that has a low Exploitability) so we don't really gain much by keeping them until the final release but we risk a lot from skipping the general QA process. -- Ferenc Kovács @Tyr43l - http://tyrael.hu --- ## #96637 — Pierre Joye — 2016-10-29T10:11:03+00:00 URL: https://externals.io/message/96574#96637 · In reply to: #96635 Hi, > > On Fri, Oct 28, 2016 at 11:18 AM, Remi Collet > wrote: > > > […] assume > > […] setting > > […] not > > […] overflows > > […] > I agree with Remi, these should be fixed via the normal development process > so we can catch any issues during the RC. > These are basically the same issue, they can be exploited the same way > (which I agree that has a low Exploitability) so we don't really gain much > by keeping them until the final release but we risk a lot from skipping the > general QA process. Thanks Stas for bringing that up. It is indeed a case by case decision, however I fully agree with Remi and Tyrael here, for the cases described by Stas initial post (or similar). It is extremely hard to do it in a short time during final phases, let alone the risk to create more damages by applying a bad fix. About marking them as low security bugs or not. I have no strong opinion. Maybe we could define what is a production environment and then define bugs affecting this environment as security issues. Cheers Pierre --- ## #96641 — Stanislav Malyshev — 2016-10-30T05:21:23+00:00 URL: https://externals.io/message/96574#96641 · In reply to: #96592 Hi! So I wrote a first version of the document Anatol mentioned: https://wiki.php.net/security Please comment. Fixes to the grammar and typos are especially welcome (you can just do them in the wiki without asking :) -- Stas Malyshev smalyshev@gmail.com --- ## #96686 — Anatol Belski — 2016-11-01T01:47:28+00:00 URL: https://externals.io/message/96574#96686 · In reply to: #96641 Hi Stas, > -----Original Message----- > From: Stanislav Malyshev [mailto:smalyshev@gmail.com] > Sent: Sunday, October 30, 2016 6:21 AM > To: Anatol Belski ; 'PHP Internals' > > Cc: 'Remi Collet' > Subject: Re: [PHP-DEV] bug classification discussion > > Hi! > > So I wrote a first version of the document Anatol mentioned: > > https://wiki.php.net/security > > Please comment. Fixes to the grammar and typos are especially welcome (you > can just do them in the wiki without asking :) > I couldn't catch any syntax/grammar mistakes, and the sense is good AFM. I'd suggest to link this page on bugs.php.net and maybe elsewhere like in the manual, as a guidelines for security bug reporting. Regards Anatol --- ## #96691 — Joe Watkins — 2016-11-01T06:22:30+00:00 URL: https://externals.io/message/96574#96691 · In reply to: #96686 Morning, I did review and reformat the document, so that we have lists ... lists of things are easier to retain in memory than paragraphs of things :) Feel free to review the review. Cheers Joe > Hi Stas, > > > […] > (you > > […] > I couldn't catch any syntax/grammar mistakes, and the sense is good AFM. > I'd suggest to link this page on bugs.php.net and maybe elsewhere like in > the manual, as a guidelines for security bug reporting. > > Regards > > Anatol --- ## #96693 — Nikita Popov — 2016-11-01T09:32:10+00:00 URL: https://externals.io/message/96574#96693 · In reply to: #96641 On Sun, Oct 30, 2016 at 6:21 AM, Stanislav Malyshev wrote: > Hi! > > So I wrote a first version of the document Anatol mentioned: > > https://wiki.php.net/security > > Please comment. Fixes to the grammar and typos are especially welcome > (you can just do them in the wiki without asking :) > It would be nice to add specific examples (e.g. the string overflow case to low). I'm also wondering under which category `unserialize()` issues would (usually) fall. I'd assume "low" (because requires documented insecure code + well known class of vulnerabilities). Nikita --- ## #96696 — Anatol Belski — 2016-11-01T13:27:28+00:00 URL: https://externals.io/message/96574#96696 · In reply to: #96693 > -----Original Message----- > From: Nikita Popov [mailto:nikita.ppv@gmail.com] > Sent: Tuesday, November 1, 2016 10:32 AM > To: Stanislav Malyshev > Cc: Anatol Belski ; PHP Internals > ; Remi Collet > Subject: Re: [PHP-DEV] bug classification discussion > > On Sun, Oct 30, 2016 at 6:21 AM, Stanislav Malyshev > wrote: > > > […] > > It would be nice to add specific examples (e.g. the string overflow case to low). > > I'm also wondering under which category `unserialize()` issues would > (usually) fall. I'd assume "low" (because requires documented insecure code > + well known class of vulnerabilities). > Yet one thing seems to be missing - security issue, that only concerns an unstable branch. Those are probably can be handled as low severity, as any pre GA or master are not for production anyway. Still they should not be disclosed until fixed, but should be fine to fix at any point of time. Regards Anatol --- ## #96698 — Stanislav Malyshev — 2016-11-01T17:13:42+00:00 URL: https://externals.io/message/96574#96698 · In reply to: #96693 Hi! > I'm also wondering under which category `unserialize()` issues would > (usually) fall. I'd assume "low" (because requires documented insecure > code + well known class of vulnerabilities). I'd say medium. While it's documented that unserializing external strings is unsafe, there is code out there that does exactly that. Especially older code from times before JSON was mainstream. -- Stas Malyshev smalyshev@gmail.com --- ## #96699 — Stanislav Malyshev — 2016-11-01T17:14:35+00:00 URL: https://externals.io/message/96574#96699 · In reply to: #96696 Hi! > Yet one thing seems to be missing - security issue, that only > concerns an unstable branch. Those are probably can be handled as low > severity, as any pre GA or master are not for production anyway. > Still they should not be disclosed until fixed, but should be fine to > fix at any point of time. Makes sense. Please feel free to add, or I'll add it a bit later. -- Stas Malyshev smalyshev@gmail.com --- ## #96700 — Anatol Belski — 2016-11-01T17:55:08+00:00 URL: https://externals.io/message/96574#96700 · In reply to: #96698 Hi Stas, > -----Original Message----- > From: Stanislav Malyshev [mailto:smalyshev@gmail.com] > Sent: Tuesday, November 1, 2016 6:14 PM > To: Nikita Popov > Cc: Anatol Belski ; PHP Internals > ; Remi Collet > Subject: Re: [PHP-DEV] bug classification discussion > > Hi! > > > […] > > I'd say medium. While it's documented that unserializing external strings is > unsafe, there is code out there that does exactly that. > Especially older code from times before JSON was mainstream. > I can do that. Regards Anatol --- ## #96701 — Yasuo Ohgaki — 2016-11-01T20:44:06+00:00 URL: https://externals.io/message/96574#96701 · In reply to: #96641 Hi Stas, > So I wrote a first version of the document Anatol mentioned: > > https://wiki.php.net/security > > Please comment. Fixes to the grammar and typos are especially welcome > (you can just do them in the wiki without asking :) Nice work! Reasonable content. It may better to include Q&A for open_basedir that bypassing open_basedir restrictions via module features are not considered as security bugs. open_basedir restriction is to mitigate impact on unwanted PHP code execution, not a complete solution. We have "security bug" in document also. It may be better to mention them and encourage users to report this kind of bug also. Regards, -- Yasuo Ohgaki yohgaki@ohgaki.net --- ## #96710 — Jakub Zelenka — 2016-11-02T19:36:13+00:00 URL: https://externals.io/message/96574#96710 · In reply to: #96574 Hi, On Mon, Oct 24, 2016 at 6:23 AM, Stanislav Malyshev wrote: > Hi! > > We have had a bunch of bugs recently which are essentially one and the > same issue: PHP 5.6 allows only int-sized strings, but many functions > don't check the size of the string they produce. This can lead to int > overflows inside php and also can break other libraries that also assume > string sizes are ints and this can cause all kinds of weirdness. > However, these bugs are very unlikely to manifest in production setting > for one simple reason - they require PHP to run with no memory limit, > and I haven't seen many setups that run with no memory limit. I'm not > going to go into specifics here, since some of the issues are still not > fixed, but you can talk to me privately if you need examples or browse > changelogs of later 5.6 releases. > > A twin brother of this is in 7.0 where there are just integer overflows > in string size calculations. Usually that requires huge strings as > inputs, so also requires running with no memory limit. > > These bugs are now treated as security issues, due to the fact that in > theory somebody might be running with no memory limit and get huge > string as an input from user. However, it was questioned that we indeed > should treat them so, due to the fact that encountering them in > production is unlikely, and due to the fact that they require patching > in many places, and merging those fixes out-of-band creates significant > potential for bugs. > > I would probably treat them as a low severity issues. It means just not disclose them until they are fixed and let RM decide if they want to pull them to the branches for security fixes only. The thing is that it might take time till they are fixed so better not to keep them publicly visible. Cheers --- ## #96802 — Anatol Belski — 2016-11-09T23:49:27+00:00 URL: https://externals.io/message/96574#96802 · In reply to: #96710 Hi, > -----Original Message----- > From: jakub.php@gmail.com [mailto:jakub.php@gmail.com] On Behalf Of Jakub > Zelenka > Sent: Wednesday, November 2, 2016 8:36 PM > To: Stanislav Malyshev > Cc: PHP Internals ; Remi Collet > > Subject: Re: [PHP-DEV] bug classification discussion > > Hi, > > On Mon, Oct 24, 2016 at 6:23 AM, Stanislav Malyshev > wrote: > > > […] > I would probably treat them as a low severity issues. It means just not disclose > them until they are fixed and let RM decide if they want to pull them to the > branches for security fixes only. The thing is that it might take time till they are > fixed so better not to keep them publicly visible. > It looks, like there's the consensus on https://wiki.php.net/security in its current form, so probably no additional measures like voting are needed. Given that, I would suggest these classifications to officially become effective, so we start to apply them already for the subsequent releases. Are there any objections? Thanks Anatol