Mandriva Linux Security Advisory : dbus (MDVSA-2014:214)
Medium Nessus Plugin ID 79322
SynopsisThe remote Mandriva Linux host is missing one or more security updates.
DescriptionUpdated dbus packages fixes the following security issues :
Alban Crequy and Simon McVittie discovered several vulnerabilities in the D-Bus message daemon :
On 64-bit platforms, file descriptor passing could be abused by local users to cause heap corruption in dbus-daemon, leading to a crash, or potentially to arbitrary code execution (CVE-2014-3635).
A denial-of-service vulnerability in dbus-daemon allowed local attackers to prevent new connections to dbus-daemon, or disconnect existing clients, by exhausting descriptor limits (CVE-2014-3636).
Malicious local users could create D-Bus connections to dbus-daemon which could not be terminated by killing the participating processes, resulting in a denial-of-service vulnerability (CVE-2014-3637).
dbus-daemon suffered from a denial-of-service vulnerability in the code which tracks which messages expect a reply, allowing local attackers to reduce the performance of dbus-daemon (CVE-2014-3638).
dbus-daemon did not properly reject malicious connections from local users, resulting in a denial-of-service vulnerability (CVE-2014-3639).
The patch issued by the D-Bus maintainers for CVE-2014-3636 was based on incorrect reasoning, and does not fully prevent the attack described as CVE-2014-3636 part A, which is repeated below. Preventing that attack requires raising the system dbus-daemon's RLIMIT_NOFILE (ulimit -n) to a higher value.
By queuing up the maximum allowed number of fds, a malicious sender could reach the system dbus-daemon's RLIMIT_NOFILE (ulimit -n, typically 1024 on Linux). This would act as a denial of service in two ways :
- new clients would be unable to connect to the dbus-daemon
- when receiving a subsequent message from a non-malicious client that contained a fd, dbus-daemon would receive the MSG_CTRUNC flag, indicating that the list of fds was truncated; kernel fd-passing APIs do not provide any way to recover from that, so dbus-daemon responds to MSG_CTRUNC by disconnecting the sender, causing denial of service to that sender.
This update also resolves the CVE-2014-7824 security vulnerability.
SolutionUpdate the affected packages.