A trivial to reach stack-based buffer overflow is present in libpam on Solaris. The vulnerable code exists in pam_framework.c parse_user_name() which allocates a fixed size buffer of 512 bytes on the stack and parses a username supplied to PAM modules (such as authtok_get used by SunSSH). This issue can be reached remotely pre-authentication via SunSSH when “keyboard-interactive” is enabled to use PAM based authentication. The vulnerability was discovered being actively exploited by FireEye in the wild and is part of an APT toolkit called “EVILSUN”. The vulnerability is present in both SPARC/x86 versions of Solaris and others (eg. illumos). This exploit uses ROP gadgets to disable nxstack through mprotect on x86 and a helper shellcode stub. Tested against latest Solaris 10 without patch applied and the configuration is vulnerable in a default vanilla install. This exploit requires libssh2, the vulnerability has been identified and confirmed reachable on Solaris 10 through 11.0.
advisories | CVE-2020-14871