Red Hat Bugzilla – Full Text Bug Listing
|Summary:||CVE-2014-0022 yum: yum-cron installs unsigned packages|
|Product:||[Other] Security Response||Reporter:||Vincent Danen <vdanen>|
|Component:||vulnerability||Assignee:||Red Hat Product Security <security-response-team>|
|Status:||CLOSED ERRATA||QA Contact:|
|Version:||unspecified||CC:||admiller, aneelica, ffesti, james.antill, jkurik, jrusnack, jzeleny, packaging-team-maint, pfrields, vkrizan|
|Fixed In Version:||Doc Type:||Bug Fix|
It was discovered that yum-updatesd did not properly perform RPM package signature checks. When yum-updatesd was configured to automatically install updates, a remote attacker could use this flaw to install a malicious update on the target system using an unsigned RPM or an RPM signed with an untrusted key.
|Last Closed:||2014-08-04 23:51:01 EDT||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Bug Depends On:||1052440, 1052994, 1053202, 1125185|
Description Vincent Danen 2014-01-23 18:16:21 EST
Gabriel VLASIU reported  that yum-cron would install unsigned RPM packages that yum itself would refuse to install. The yum-cron code is based on that in yum-updatesd.py. This is due to the installUpdates() function (processPkgs() in yum-updatesd.py) failing to fully check the return code of the called sigCheckPkg() function. sigCheckPkg() is described thus: def sigCheckPkg(self, po): """Verify the GPG signature of the given package object. :param po: the package object to verify the signature of :return: (result, error_string) where result is:: 0 = GPG signature verifies ok or verification is not required. 1 = GPG verification failed but installation of the right GPG key might help. 2 = Fatal GPG verification error, give up. """ However, the processPkgs() and installUpdates() calling function do not account for return code 2: def processPkgs(self, dlpkgs): ... for po in dlpkgs: result, err = self.updd.sigCheckPkg(po) if result == 0: continue elif result == 1: try: self.updd.getKeyForPackage(po) except yum.Errors.YumBaseError, errmsg: self.failed([str(errmsg)]) and: def installUpdates(self, emit): ... for po in dlpkgs: result, err = self.sigCheckPkg(po) if result == 0: continue elif result == 1: try: self.getKeyForPackage(po) except yum.Errors.YumBaseError, errmsg: self.emitUpdateFailed(errmsg) return False yum-cron.py replaced yum-cron.sh in Fedora 19 (3.4.3-47); earlier versions of Fedora use yum-updatesd. This has been corrected upstream  and in Fedora via yum-3.4.3-132.fc19 and yum-3.4.3-130.fc20. This does not affect Red Hat Enterprise Linux 6 as it used neither yum-updatesd nor yum-cron; it used a shellscript that called yum itself to do updates.  https://bugzilla.redhat.com/show_bug.cgi?id=1052440  http://yum.baseurl.org/gitweb?p=yum.git;a=commitdiff;h=9df69e579496ccb6df5c3f5b5b7bab8d648b06b4
Comment 2 Tomas Hoger 2014-07-31 05:15:01 EDT
The comment 0 above explains that Red Hat Enterprise Linux 6 was not affected, as it did not include vulnerable version of yum-updatesd or yum-cron. This issue was resolved in yum-cron shipped as part of Red Hat Enterprise Linux 7 before its initial release. Statement: This issue did not affect the versions of yum as shipped with Red Hat Enterprise Linux 6 and 7.
Comment 3 Tomas Hoger 2014-07-31 05:20:11 EDT
It should also be noted that in their default configuration, yum-updatesd and yum-cron are not configured to automatically install available updates. They are configured to provide notification of updates availability. yum-cron is also configured to download updated packages, but not install them.
Comment 8 errata-xmlrpc 2014-08-04 23:34:46 EDT
This issue has been addressed in following products: Red Hat Enterprise Linux 5 Via RHSA-2014:1004 https://rhn.redhat.com/errata/RHSA-2014-1004.html
Comment 9 Martin Prpič 2014-08-05 03:30:58 EDT
IssueDescription: It was discovered that yum-updatesd did not properly perform RPM package signature checks. When yum-updatesd was configured to automatically install updates, a remote attacker could use this flaw to install a malicious update on the target system using an unsigned RPM or an RPM signed with an untrusted key.