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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.2899 QEMU: usb: out-of-bounds r/w access issue 25 August 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: QEMU Publisher: Xen Operating System: Windows UNIX variants (UNIX, Linux, OSX) Impact/Access: Execute Arbitrary Code/Commands -- Existing Account Denial of Service -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2020-14364 Original Bulletin: http://xenbits.xen.org/xsa/advisory-335.html - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory CVE-2020-14364 / XSA-335 version 2 QEMU: usb: out-of-bounds r/w access issue UPDATES IN VERSION 2 ==================== Don't break the DSO by eliding the SoB on the patch. Update Vulnerable Systems section. Public release. ISSUE DESCRIPTION ================= An out-of-bounds read/write access issue was found in the USB emulator of the QEMU. It occurs while processing USB packets from a guest, when 'USBDevice->setup_len' exceeds the USBDevice->data_buf[4096], in do_token_{in,out} routines. IMPACT ====== A guest user may use this flaw to crash the QEMU process resulting in DoS OR potentially execute arbitrary code with the privileges of the QEMU process on the host. VULNERABLE SYSTEMS ================== All versions of Qemu shipped with in-support versions of Xen are vulnerable. This includes both qemu-traditional and qemu-xen. The vulnerability can only be exploited when Qemu is used as a device model. This configuration is only used by default for x86 HVM guests. x86 PV, PVH and ARM guest do not use a device model by default. Guests configured to use a Qemu stubdomain contain the code execution within the stubdomain, and are therefore not considered vulnerable. MITIGATION ========== No mitigation is available. CREDITS ======= This issue was discovered by Xiao Wei of Qihoo 360 Inc. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. Note that patches for released versions are generally prepared to apply to the stable branches, and may not apply cleanly to the most recent release tarball. Downstreams are encouraged to update to the tip of the stable branch before applying these patches. xsa335-qemu.patch QEMU xsa335-trad.patch Xen unstable (SUPPORT.md update only) $ sha256sum xsa335* 3af5f30c4fd21e3679fb749659f9e59d0ff335d092254352e128e7fee3340c41 xsa335-qemu.patch 2ed7b8bac4c473c6f89173a73485904be16785eb29ee18e189717d201381f27f xsa335-trad.patch $ "QEMU XEN TRADITIONAL" ====================== This version of qemu is provided by the Xen Project for use as a device model stub domain. In that configuration, there is not a security problem and no action is needed. But in other configurations, this version of qemu is lacking many security fixes. It is beyond the capacity of the Xen Project Security Team to address these. There is therefore no code resolution to XSA-335 for users of qemu-xen-traditional who are not using device model stub domains. The patch xsa335-trad.patch included in this advisory is merely an update for Xen's SUPPORT.md to document this situation. 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----- iQFABAEBCAAqFiEEI+MiLBRfRHX6gGCng/4UyVfoK9kFAl9Dr+0MHHBncEB4ZW4u b3JnAAoJEIP+FMlX6CvZ274H/3FIK/DecsmdqVFs9UjqCi+RABmz6dFsgUxQYH9c ysZvN7R/BTR1m425+7tlPK1oglkFkHt6C9snc3+kTh/Bl5ktXakgVacoR6yeTh88 1yJQC3JmG9OaXGS4AR9hmE+Wg0XTlrmvzPMFxtWv055kpPVEG6FWhnhV8d0FavoI RWnlelNSkXgai5zWlAqhF8jzR4EeEmOp4f/BtQX/cjZAodXZSYMvLW1zy3vx4Wik ZpL4qkJLE9GHOYZF9Ng8zwWx7c1CIi76zwdUvUgPu6IjTBIpo0LPZxlkbF+CqYcp rVFaAy7j7+xMOOJntlN2a/NAxD4zs+sCLF1legrfi+9uMH4= =bMZs - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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