Re: ownCloud Unencrypted Private Key Exposure
Hi, thank you for this announcement. I have a (very naive) question about this. As a consequence of this vulnerability an attacker with access to the ownCloud server's file system can compromise the encrypted data stored on the server. There does not seem to be a workaround for that and there will be no fix. Thus, data on an ownCloud server is always accessible to an attacker with access to the file system, regardless of whether ownCloud's encryption feature is enabled or not. Is that correct so far? It seems to me that one of the encryption feature's main purposes is to prevent an attacker with access to the server's file system from immediate access to the user data. If my understanding above is true, then this purpose is void since the encryption is useless in that scenario. If this is somehow not part of the vendor's threat model, isn't it at least an important restriction? Or did I completely misunderstand something? Regards Frank Am 04.08.2014 08:38, schrieb Senderek Web Security: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Senderek Web Security - Security Advisory ownCloud Unencrypted Private Key Exposure = https://senderek.ie/archive/2014/owncloud_unencrypted_private_key_exposure.php Revision: 1.00 Last Updated: 3 Aug 2014 Summary: In consequence of an insufficient threat model, ownCloud is storing all user's private RSA keys in clear text in PHP session files. These unencrypted private keys can be accessed by every web application that has the privilege of the web server user. The affected files exposing cryptographic keys will be stored in the PHP session directory for a number of hours until they are removed. This issue was reported to ownCloud via encrypted email on Tue, 11 Mar 2014. I received a reply to this report from the vendor on Wed, 12 Mar 2014. On Tue, 22 July 2014 the vendor confirmed, that they will not address this problem, because the protection of user encrypted files from remote attackers that have read access to the file system with web server privilege is not - and will not be - part of their threat model. Consequently, the vendor does not consider this to be a vulnerability or security issue. Severity: High Affected Software Versions: All versions of ownCloud since the introduction of the encryption module in version 5.0.7 including version 7.0.0. Impact: An attacker, who is able to read the PHP session files by exploiting another web application that is running on the ownCloud server, will be able to gather the unencrypted private key of every ownCloud user. All encrypted files that are stored in a user's home directory can be decrypted with this RSA private key, stored in the PHP session files in plain text. If the user's encrypted files are synced to other devices or shared with other servers - for hosting or backup - an attacker will be able to decrypt all user data that is being intercepted, even if the attacker has no longer access to the server's file system. Fixes: In addition to the ownCloud encryption module users are advised to encrypt their sensitive files separately with a standard server-side encryption mechanism like GnuPG using a passphrase, that is not stored on the server except while being used in memory. One software solution that extends ownCloud with GnuPG-based server-side encryption can be downloaded here: https://senderek.ie/downloads/release/cloud/wee-owncloud.tar A detailed installation tutorial is available at: https://senderek.ie/wee/cloud/wee-owncloud.php This general web application extension addresses a more comprehensive threat model, that includes the possibility of read-access to web server accessible files on the server. However, it does not protect against malicious actions of server admins, as this cannot be prevented by web applications. Security Advice Policy: Complete information about reporting security vulnerabilities can be found here: https://senderek.ie/responsible.disclosure.policy.php All information in this security advisory is copyrighted because of the time and effort in analysing and documenting the vulnerability described here. -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJT3lsOAAoJECyxzx4lRhdKI30QAKrVrr9nFO3+qdX6a0V6sJoy sJUaqTbW9i1EI8IId2Vd1oh5GHJVq6BI9mnO+dTX+Y32B/cct1vfe+7Xfzhl9sGM g0Z3vMsnm2MbEW2AjJTC3CCCHsLt3oSwpsevQaQ2BRZbUgSS1VIYCA6zACLJgzHr oX/ExHXqdZ8Slol4N+3h9q5+DT2VjVgoBdNXWIeq0nd6iYbAlFS9YLECDAnFPtAl OW05Z9m1wkMSxW1NiJPrQRmHn7YY41/SH7lgyIX0+lpi0h2D/LzAvpoVDRQL1j9A aTP3B3xjCW8sQShKd4y8xLKQq2023L8ucy+h6anWbJCliIbK5cnXsjBgIJ
Re: ownCloud Unencrypted Private Key Exposure
Hello, If by acces to the file system you mean with all administrative privileges, yes but only if there are users sessions in php session storage to decrypt the files for that user. You can have multiple websites on the FS if they do not share the tmp session storage for php there are no vulnerability as it would require to access the session for owncloud user. Regards, Anthony Dubuissez Le 4 août 2014 à 16:00, Frank Stanek a écrit : > Hi, > > thank you for this announcement. I have a (very naive) question about this. > As a consequence of this vulnerability an attacker with access to the > ownCloud server's file system can compromise the encrypted data stored on the > server. There does not seem to be a workaround for that and there will be no > fix. Thus, data on an ownCloud server is always accessible to an attacker > with access to the file system, regardless of whether ownCloud's encryption > feature is enabled or not. Is that correct so far? > > It seems to me that one of the encryption feature's main purposes is to > prevent an attacker with access to the server's file system from immediate > access to the user data. If my understanding above is true, then this purpose > is void since the encryption is useless in that scenario. If this is somehow > not part of the vendor's threat model, isn't it at least an important > restriction? Or did I completely misunderstand something? > > Regards > Frank > > > Am 04.08.2014 08:38, schrieb Senderek Web Security: >> -BEGIN PGP SIGNED MESSAGE- >> Hash: SHA1 >> >> >> Senderek Web Security - Security Advisory >> >> ownCloud Unencrypted Private Key Exposure >> = >> >> https://senderek.ie/archive/2014/owncloud_unencrypted_private_key_exposure.php >> >> Revision: 1.00 >> Last Updated: 3 Aug 2014 >> >> >> Summary: >> >>In consequence of an insufficient threat model, ownCloud is >> storing all user's >>private RSA keys in clear text in PHP session files. >>These unencrypted private keys can be accessed by every web >> application that >>has the privilege of the web server user. The affected files >> exposing cryptographic >>keys will be stored in the PHP session directory for a number >> of hours until they >>are removed. >> >>This issue was reported to ownCloud via encrypted email on >> Tue, 11 Mar 2014. >>I received a reply to this report from the vendor on Wed, 12 >> Mar 2014. >> >>On Tue, 22 July 2014 the vendor confirmed, that they will not >> address this problem, >>because the protection of user encrypted files from remote >> attackers that have >>read access to the file system with web server privilege is >> not - and will not be - >>part of their threat model. Consequently, the vendor does not >> consider this to be >>a vulnerability or security issue. >> >> Severity: High >> >> >> Affected Software Versions: >> >>All versions of ownCloud since the introduction of the >> encryption module in >>version 5.0.7 including version 7.0.0. >> >> >> Impact: >> >>An attacker, who is able to read the PHP session files by >> exploiting another web >>application that is running on the ownCloud server, will be >> able to gather the >>unencrypted private key of every ownCloud user. >>All encrypted files that are stored in a user's home >> directory can be decrypted >>with this RSA private key, stored in the PHP session files in >> plain text. >>If the user's encrypted files are synced to other devices or >> shared with >>other servers - for hosting or backup - an attacker will be >> able to decrypt all >>user data that is being intercepted, even if the attacker has >> no longer access to >>the server's file system. >> >> >> Fixes: >> >>In addition to the ownCloud encryption module users are >> advised to encrypt their >>sensitive files separately with a standard server-side >> encryption mechanism like >>GnuPG using a passphrase, that is not stored on the server >> except while being used >>in memory. >> >>One software solution that extends ownCloud with GnuPG-based >> server-side encryption >>can be downloaded here: >> >>https://senderek.ie/downloads/release/cloud/wee-owncloud.tar >> >>A detailed installation tutorial is available at: >> >>https://senderek.ie/wee/cloud/wee-owncloud.php >> >>This general web application extension addresses a more >> comprehensive threat model, >>that includes the possibility of read-access to web server >> accessible files on the >>server. However, it does not protect against malicious >> actions of server admins, >>as this cannot be prevented by web applications. >> >> >> Security Advice Policy: >> >>Complete in
Re: ownCloud Unencrypted Private Key Exposure
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, A valid concern. HTTPS should be used to secure traffic from a client to the server, solving any problems related to eavesdropping. Encrypting the content of the account data should solve two problems. 1. Secure data from curious system administrators. 2. Secure data in case of an account breach, Lost password or phishing (ect.) 3. Secure data that is copied off the server and taken offsite. The current solution doesn't solve any of those problems. Firstly the users password is the encryption key. Secondly, in the case of number 3, an attacker that can get your raw data will either have your account password or server side access. - From the OwnCloud Manual: http://doc.owncloud.org/server/6.0/user_manual/files/encryption.html "Server-Side encryption is especially useful if you use external storages. This way you can make sure that the storage provider is not able to read your data." I'm not quite sure what they are suggesting, because if we read a little further: "Encryption and decryption always happens server-side. This enables the user to continue to use all the other apps to view and edit their data. But this also means that the server administrator could intercept your data." With that in mind it would be nice to get some clarification as to what threat the encryption solution is designed to mitigate. Jack. Den 04.08.2014 16:00, skrev Frank Stanek: > Hi, > > thank you for this announcement. I have a (very naive) question > about this. As a consequence of this vulnerability an attacker with > access to the ownCloud server's file system can compromise the > encrypted data stored on the server. There does not seem to be a > workaround for that and there will be no fix. Thus, data on an > ownCloud server is always accessible to an attacker with access to > the file system, regardless of whether ownCloud's encryption > feature is enabled or not. Is that correct so far? > > It seems to me that one of the encryption feature's main purposes > is to prevent an attacker with access to the server's file system > from immediate access to the user data. If my understanding above > is true, then this purpose is void since the encryption is useless > in that scenario. If this is somehow not part of the vendor's > threat model, isn't it at least an important restriction? Or did I > completely misunderstand something? > > Regards Frank > > > Am 04.08.2014 08:38, schrieb Senderek Web Security: > > Senderek Web Security - Security Advisory > > ownCloud Unencrypted Private Key Exposure > = > > > https://senderek.ie/archive/2014/owncloud_unencrypted_private_key_exposure.php > > > > Revision: 1.00 Last Updated: 3 Aug 2014 > > > Summary: > > In consequence of an insufficient threat model, ownCloud is storing > all user's private RSA keys in clear text in PHP session files. > These unencrypted private keys can be accessed by every web > application that has the privilege of the web server user. The > affected files exposing cryptographic keys will be stored in the > PHP session directory for a number of hours until they are > removed. > > This issue was reported to ownCloud via encrypted email on Tue, 11 > Mar 2014. I received a reply to this report from the vendor on Wed, > 12 Mar 2014. > > On Tue, 22 July 2014 the vendor confirmed, that they will not > address this problem, because the protection of user encrypted > files from remote attackers that have read access to the file > system with web server privilege is not - and will not be - part of > their threat model. Consequently, the vendor does not consider this > to be a vulnerability or security issue. > > Severity: High > > > Affected Software Versions: > > All versions of ownCloud since the introduction of the encryption > module in version 5.0.7 including version 7.0.0. > > > Impact: > > An attacker, who is able to read the PHP session files by > exploiting another web application that is running on the ownCloud > server, will be able to gather the unencrypted private key of every > ownCloud user. All encrypted files that are stored in a user's > home directory can be decrypted with this RSA private key, stored > in the PHP session files in plain text. If the user's encrypted > files are synced to other devices or shared with other servers - > for hosting or backup - an attacker will be able to decrypt all > user data that is being intercepted, even if the attacker has no > longer access to the server's file system. > > > Fixes: > > In addition to the ownCloud encryption module users are advised to > encrypt their sensitive files separately with a standard > server-side encryption mechanism like GnuPG using a passphrase, > that is not stored on the server except while being used in > memory. > > One software solution that extends ownCloud with GnuPG-based > server-side encryption can be downloaded here: > > > https:
Re: ownCloud Unencrypted Private Key Exposure
Hi, thanks to everyone for the input. Agreed, some clarification would be nice. I have verified that ownCloud 7.0.1 on Debian Wheezy is vulnerable, happily exposing unencrypted 4096 bit RSA private keys in PHP session files upon user login. But it seems that an attacker needs three things to decrypt the user's data. 1) The encrypted data 2) For each encrypted file, he needs a corresponding key file used for the symmetric file encryption 3) The leaked RSA private key which is used to encrypt/decrypt the key files If we take that into account, it _may_ be possible to make sense of the two excerpts from the manual which you quoted. Let's say the user data and file encryption key files are stored in one directory tree which is on "external storage". Let's then say that the PHP session files are created in a different directory tree on the local file system. This means two things. 1) The provider of the external storage has access to the encrypted data and the encrypted file keys, but cannot access the RSA private keys. Thus he will not be able to decrypt the data. 2) The administrator of the ownCloud server however has access to all three if the "external storage" is mounted into the file system. So he has everything he needs to decrypt or "intercept" user data. That is highly speculative on my part though and implies a distinction between the provider of the "external storage" and the "server administrator". If it is really meant like that though, it still seems like a huge restriction to me, and it's hard for me to believe that this is actually as intended. Because I'd think that most people would assume that if there is server side encryption, it is there to protect the data from anyone with filesystem access. And that includes the server administrator in my book. Regards Frank Am 05.08.2014 20:09, schrieb Jack Brennan: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, A valid concern. HTTPS should be used to secure traffic from a client to the server, solving any problems related to eavesdropping. Encrypting the content of the account data should solve two problems. 1. Secure data from curious system administrators. 2. Secure data in case of an account breach, Lost password or phishing (ect.) 3. Secure data that is copied off the server and taken offsite. The current solution doesn't solve any of those problems. Firstly the users password is the encryption key. Secondly, in the case of number 3, an attacker that can get your raw data will either have your account password or server side access. - From the OwnCloud Manual: http://doc.owncloud.org/server/6.0/user_manual/files/encryption.html "Server-Side encryption is especially useful if you use external storages. This way you can make sure that the storage provider is not able to read your data." I'm not quite sure what they are suggesting, because if we read a little further: "Encryption and decryption always happens server-side. This enables the user to continue to use all the other apps to view and edit their data. But this also means that the server administrator could intercept your data." With that in mind it would be nice to get some clarification as to what threat the encryption solution is designed to mitigate. Jack. Den 04.08.2014 16:00, skrev Frank Stanek: Hi, thank you for this announcement. I have a (very naive) question about this. As a consequence of this vulnerability an attacker with access to the ownCloud server's file system can compromise the encrypted data stored on the server. There does not seem to be a workaround for that and there will be no fix. Thus, data on an ownCloud server is always accessible to an attacker with access to the file system, regardless of whether ownCloud's encryption feature is enabled or not. Is that correct so far? It seems to me that one of the encryption feature's main purposes is to prevent an attacker with access to the server's file system from immediate access to the user data. If my understanding above is true, then this purpose is void since the encryption is useless in that scenario. If this is somehow not part of the vendor's threat model, isn't it at least an important restriction? Or did I completely misunderstand something? Regards Frank Am 04.08.2014 08:38, schrieb Senderek Web Security: Senderek Web Security - Security Advisory ownCloud Unencrypted Private Key Exposure = https://senderek.ie/archive/2014/owncloud_unencrypted_private_key_exposure.php Revision: 1.00 Last Updated: 3 Aug 2014 Summary: In consequence of an insufficient threat model, ownCloud is storing all user's private RSA keys in clear text in PHP session files. These unencrypted private keys can be accessed by every web application that has the privilege of the web server user. The affected files exposing cryptographic keys will be stored in the PHP session directory for a number of hours until they are remov
RE: ownCloud Unencrypted Private Key Exposure
Hello, Cloud providers are always assuring about unbeatable security, but try to get any clause in SLA that they will pay for data losses. That shows how they trust their services. Concerning encryption, what is in the manual is ridiculous. The only one way to keep your data secure is to encrypt and decrypt locally, and keep your key local. Only that guarantee integrity of your own data on external/cloud storage. I think it is security ABC. Of course, as I said, it does not guarantee availability. Do not trust external encryption as in this case they keep your key, and we see how this vendor is good in that. Mikhail Utin, CISSP -Original Message- From: Jack Brennan [mailto:m...@sourcenix.com] Sent: Tuesday, August 05, 2014 2:10 PM To: bugtraq@securityfocus.com Subject: Re: ownCloud Unencrypted Private Key Exposure -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, A valid concern. HTTPS should be used to secure traffic from a client to the server, solving any problems related to eavesdropping. Encrypting the content of the account data should solve two problems. 1. Secure data from curious system administrators. 2. Secure data in case of an account breach, Lost password or phishing (ect.) 3. Secure data that is copied off the server and taken offsite. The current solution doesn't solve any of those problems. Firstly the users password is the encryption key. Secondly, in the case of number 3, an attacker that can get your raw data will either have your account password or server side access. - From the OwnCloud Manual: http://doc.owncloud.org/server/6.0/user_manual/files/encryption.html "Server-Side encryption is especially useful if you use external storages. This way you can make sure that the storage provider is not able to read your data." I'm not quite sure what they are suggesting, because if we read a little further: "Encryption and decryption always happens server-side. This enables the user to continue to use all the other apps to view and edit their data. But this also means that the server administrator could intercept your data." With that in mind it would be nice to get some clarification as to what threat the encryption solution is designed to mitigate. Jack. Den 04.08.2014 16:00, skrev Frank Stanek: > Hi, > > thank you for this announcement. I have a (very naive) question about > this. As a consequence of this vulnerability an attacker with access > to the ownCloud server's file system can compromise the encrypted data > stored on the server. There does not seem to be a workaround for that > and there will be no fix. Thus, data on an ownCloud server is always > accessible to an attacker with access to the file system, regardless > of whether ownCloud's encryption feature is enabled or not. Is that > correct so far? > > It seems to me that one of the encryption feature's main purposes is > to prevent an attacker with access to the server's file system from > immediate access to the user data. If my understanding above is true, > then this purpose is void since the encryption is useless in that > scenario. If this is somehow not part of the vendor's threat model, > isn't it at least an important restriction? Or did I completely > misunderstand something? > > Regards Frank > > > Am 04.08.2014 08:38, schrieb Senderek Web Security: > > Senderek Web Security - Security Advisory > > ownCloud Unencrypted Private Key Exposure > = > > > https://senderek.ie/archive/2014/owncloud_unencrypted_private_key_expo > sure.php > > > > Revision: 1.00 Last Updated: 3 Aug 2014 > > > Summary: > > In consequence of an insufficient threat model, ownCloud is storing > all user's private RSA keys in clear text in PHP session files. > These unencrypted private keys can be accessed by every web > application that has the privilege of the web server user. The > affected files exposing cryptographic keys will be stored in the PHP > session directory for a number of hours until they are removed. > > This issue was reported to ownCloud via encrypted email on Tue, 11 Mar > 2014. I received a reply to this report from the vendor on Wed, > 12 Mar 2014. > > On Tue, 22 July 2014 the vendor confirmed, that they will not address > this problem, because the protection of user encrypted files from > remote attackers that have read access to the file system with web > server privilege is not - and will not be - part of their threat > model. Consequently, the vendor does not consider this to be a > vulnerability or security issue. > > Severity: High > > > Affected Software Versions: > > All versions of ownCloud since the introduction of the encr
RE: ownCloud Unencrypted Private Key Exposure
What is said below actually does not matter. Having encrypted USER data files and USER encryption key under the same VENDOR administrative control denies encryption as means of securing data. Unless you really trust the VENDOR. But then it is about TRUST, which is not SECURITY. If the VENDOR of external service specifically explains and provides a proof that they use another party for keeping keys, and this company does not use the VENDOR's storage, then it works. BTW, insider threat risk is much higher than hacking. Because the door is already wide open. Mikhail Utin, CISSP -Original Message- From: Anthony Dubuissez [mailto:anthony.dubuis...@webera.fr] Sent: Tuesday, August 05, 2014 9:14 AM To: Frank Stanek Cc: bugtraq@securityfocus.com Subject: Re: ownCloud Unencrypted Private Key Exposure Hello, If by acces to the file system you mean with all administrative privileges, yes but only if there are users sessions in php session storage to decrypt the files for that user. You can have multiple websites on the FS if they do not share the tmp session storage for php there are no vulnerability as it would require to access the session for owncloud user. Regards, Anthony Dubuissez Le 4 août 2014 à 16:00, Frank Stanek a écrit : > Hi, > > thank you for this announcement. I have a (very naive) question about this. > As a consequence of this vulnerability an attacker with access to the > ownCloud server's file system can compromise the encrypted data stored on the > server. There does not seem to be a workaround for that and there will be no > fix. Thus, data on an ownCloud server is always accessible to an attacker > with access to the file system, regardless of whether ownCloud's encryption > feature is enabled or not. Is that correct so far? > > It seems to me that one of the encryption feature's main purposes is to > prevent an attacker with access to the server's file system from immediate > access to the user data. If my understanding above is true, then this purpose > is void since the encryption is useless in that scenario. If this is somehow > not part of the vendor's threat model, isn't it at least an important > restriction? Or did I completely misunderstand something? > > Regards > Frank > > > Am 04.08.2014 08:38, schrieb Senderek Web Security: >> -BEGIN PGP SIGNED MESSAGE- >> Hash: SHA1 >> >> >> Senderek Web Security - Security Advisory >> >> ownCloud Unencrypted Private Key Exposure >> = >> >> https://senderek.ie/archive/2014/owncloud_unencrypted_private_key_exp >> osure.php >> >> Revision: 1.00 >> Last Updated: 3 Aug 2014 >> >> >> Summary: >> >>In consequence of an insufficient threat model, ownCloud is >> storing all user's >>private RSA keys in clear text in PHP session files. >>These unencrypted private keys can be accessed by every web >> application that >>has the privilege of the web server user. The affected files >> exposing cryptographic >>keys will be stored in the PHP session directory for a number >> of hours until they >>are removed. >> >>This issue was reported to ownCloud via encrypted email on >> Tue, 11 Mar 2014. >>I received a reply to this report from the vendor on Wed, 12 >> Mar 2014. >> >>On Tue, 22 July 2014 the vendor confirmed, that they will not >> address this problem, >>because the protection of user encrypted files from remote >> attackers that have >>read access to the file system with web server privilege is >> not - and will not be - >>part of their threat model. Consequently, the vendor does not >> consider this to be >>a vulnerability or security issue. >> >> Severity: High >> >> >> Affected Software Versions: >> >>All versions of ownCloud since the introduction of the >> encryption module in >>version 5.0.7 including version 7.0.0. >> >> >> Impact: >> >>An attacker, who is able to read the PHP session files by >> exploiting another web >>application that is running on the ownCloud server, will be >> able to gather the >>unencrypted private key of every ownCloud user. >>All encrypted files that are stored in a user's home directory >> can be decrypted >>with this RSA private key, stored in the PHP session files in >> plain text. >>If the user's encrypted fi
RE: ownCloud Unencrypted Private Key Exposure - version (6.0.4) reported not vulnerable
This came into our security group when we inquired with ownCloud: It has been officially confirmed by ownCloud security team that the version (6.0.4) running on our servers is not vulnerable to this issue. "Hi --: I heard back from the Security team within ownCloud and this is not an issue in 6.0.4. -Original Message- From: Frank Stanek [mailto:fr...@frank-stanek.de] Sent: Monday, August 04, 2014 10:01 AM To: bugtraq@securityfocus.com Subject: Re: ownCloud Unencrypted Private Key Exposure Hi, thank you for this announcement. I have a (very naive) question about this. As a consequence of this vulnerability an attacker with access to the ownCloud server's file system can compromise the encrypted data stored on the server. There does not seem to be a workaround for that and there will be no fix. Thus, data on an ownCloud server is always accessible to an attacker with access to the file system, regardless of whether ownCloud's encryption feature is enabled or not. Is that correct so far? It seems to me that one of the encryption feature's main purposes is to prevent an attacker with access to the server's file system from immediate access to the user data. If my understanding above is true, then this purpose is void since the encryption is useless in that scenario. If this is somehow not part of the vendor's threat model, isn't it at least an important restriction? Or did I completely misunderstand something? Regards Frank Am 04.08.2014 08:38, schrieb Senderek Web Security: > -BEGIN PGP SIGNED MESSAGE- > Hash: SHA1 > > > Senderek Web Security - Security Advisory > > ownCloud Unencrypted Private Key Exposure > = > > > https://senderek.ie/archive/2014/owncloud_unencrypted_private_key_expo > sure.php > > Revision: 1.00 > Last Updated: 3 Aug 2014 > > > Summary: > > In consequence of an insufficient threat model, ownCloud is > storing all user's > private RSA keys in clear text in PHP session files. > These unencrypted private keys can be accessed by every web > application that > has the privilege of the web server user. The affected files > exposing cryptographic > keys will be stored in the PHP session directory for a number > of hours until they > are removed. > > This issue was reported to ownCloud via encrypted email on > Tue, 11 Mar 2014. > I received a reply to this report from the vendor on Wed, 12 > Mar 2014. > > On Tue, 22 July 2014 the vendor confirmed, that they will not > address this problem, > because the protection of user encrypted files from remote > attackers that have > read access to the file system with web server privilege is > not - and will not be - > part of their threat model. Consequently, the vendor does not > consider this to be > a vulnerability or security issue. > > Severity: High > > > Affected Software Versions: > > All versions of ownCloud since the introduction of the > encryption module in > version 5.0.7 including version 7.0.0. > > > Impact: > > An attacker, who is able to read the PHP session files by > exploiting another web > application that is running on the ownCloud server, will be > able to gather the > unencrypted private key of every ownCloud user. > All encrypted files that are stored in a user's home directory > can be decrypted > with this RSA private key, stored in the PHP session files in > plain text. > If the user's encrypted files are synced to other devices or > shared with > other servers - for hosting or backup - an attacker will be > able to decrypt all > user data that is being intercepted, even if the attacker has > no longer access to > the server's file system. > > > Fixes: > > In addition to the ownCloud encryption module users are > advised to encrypt their > sensitive files separately with a standard server-side > encryption mechanism like > GnuPG using a passphrase, that is not stored on the server > except while being used > in memory. > > One software solution that extends ownCloud with GnuPG-based > server-side encryption > can be downloaded here: > > > https://senderek.ie/downloads/release/cloud/wee-owncloud.tar > > A detailed installation tutorial is available at: > > https://senderek.ie/wee/cloud/wee-owncloud.php > > This general web application extension a
