Ubuntu Developers access to the utility /usr/bin/dmesg is restricted to users in the 'adm' group. Currently, unprivileged users in Ubuntu do not have access to /var/log/kern.log, /var/log/syslog, and system events in journalctl, but can view the kernel event log via dmesg.
The reason cited is the presence of information in the dmesg output that could be exploited by attackers to simplify the creation of privilege escalation exploits. For example, dmesg displays stack dumps in case of failures and allows the identification of address structures in the kernel, which could facilitate bypassing the KASLR mechanism. An attacker may use dmesg as feedback, gradually refining the exploit while observing oops messages in the log after unsuccessful attack attempts.
Source: opennet.ru
