Date: Tue, 14 Aug 2018 17:18:03 +0000 From: Xen.org security team <security@....org> To: xen-announce@...ts.xen.org, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, oss-security@...ts.openwall.com CC: Xen.org security team <security-team-members@....org> Subject: Xen Security Advisory 271 v2 (CVE-2018-14007) - XAPI HTTP directory traversal -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory CVE-2018-14007 / XSA-271 version 2 XAPI HTTP directory traversal UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= XAPI has an unauthenticated HTTP endpoint update/ which exports the contents of /var/update for other hosts to use. However, the resolution of . and .. in paths is performed before url unquoting is performed. This allows an attacker to traverse out of the web root. IMPACT ====== An unauthenticated user with access to the management network can read arbitrary files from the dom0 filesystem. This includes the pool secret /etc/xensource/ptoken which grants the attacker full administrator access. VULNERABLE SYSTEMS ================== All versions of XAPI since v1.13.0 are vulnerable. If the directory /var/update doesn't exist, the vulnerability is not exposed. MITIGATION ========== In the recommended configuration, the management network is isolated and isn't reachable from untrusted hosts, or by general network traffic. CREDITS ======= This issue was discovered by Ronald Volgers of Computest https://www.computest.nl/en/ RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa271-xapi.patch $ sha256sum xsa271* ffefb71cd328e0ee5654c135bf9b08f48abedd013f1c68d5589132e2a03a01f8 xsa271-xapi.patch $ REGENERATION OF POOL SECRET =========================== There are no known exploits in the wild. If there is a risk that credentials could have been stolen, they should be reset. Most credentials can be reset via normal administrative means, but the pool secret doesn't have any mechanism to reset. The following instructions should be used: 1) On all pool members, stop Xapi: # service xapi stop 2) On the pool master: # rm /etc/xensource/ptoken # /opt/xensource/libexec/genptoken -f -o /etc/xensource/ptoken 3) Copy /etc/xensource/ptoken to all pool slaves 4) On the pool master, restart the toolstack: # xe-toolstack-restart 5) On all pool slaves, restart the toolstack: # xe-toolstack-restart Once the pool secret has been regenerated, the root password can be changed with: # xe user-password-change Furthermore, consideration should be given to other credentials, such as (but not limited to) SSL keys, Storage SAN/iSCSI/NFS details, as well as secrets contained within VMs disks/snapshots/etc. DEPLOYMENT DURING EMBARGO ========================= Deployment of the patches and/or mitigations described above (or others which are substantially similar) is permitted during the embargo, even on public-facing systems with untrusted guest users and administrators. But: Distribution of updated software is prohibited (except to other members of the predisclosure list). Predisclosure list members who wish to deploy significantly different patches and/or mitigations, please contact the Xen Project Security Team. (Note: this during-embargo deployment notice is retained in post-embargo publicly released Xen Project advisories, even though it is then no longer applicable. This is to enable the community to have oversight of the Xen Project Security Team's decisionmaking.) For more information about permissible uses of embargoed information, consult the Xen Project community's agreed Security Policy: http://www.xenproject.org/security-policy.html -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBCAAGBQJbcw6vAAoJEIP+FMlX6CvZx6cH/0qaq4PDDHSrIONP7v35ZYWe nZEoA+IWk0u35t4MwSRA8qcXZ9m+d7icHdE0c5Jwdh2sBOSFKzoehCuZOFXVpYTv SHdr/J3ilZRN1KV7Zo/agZJFYClV5QxR118PnVYFqsAHVGjxh6RzazyBNPUTkoIa qw/FBQwsib4Wkj5/RPympYscxetzAUoYiFeVtTgtqknXlt3UbXqzwg/lXTrMZwtG nBSjFEW+EURlkKR0HF85mtFBmqA1I3xsKgJDaob5KWl+HmlIj0SY9knQ2le3lgxn 7zXiPSwOARg2E+vl3GB1Xd1fgcRGykBtjVWPX9uAgdb/C7qx6DN2PYEdyz1xZtI= =5lIm -----END PGP SIGNATURE----- Download attachment "xsa271-xapi.patch" of type "application/octet-stream" (1199 bytes)
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