Certain D-Link devices have a hardcoded Alphanetworks user account with TELNET access because of /etc/config/image_sign or /etc/alpha_config/image_sign. This affects DIR-600 B1 V2.01 for WW, DIR-890L A1 v1.03, DIR-615 J1 v100 (for DCN), DIR-645 A1 v1.03, DIR-815 A1 v1.01, DIR-823 A1 v1.01, and DIR-842 C1 v3.00.
D-Link DIR-600 Rev Bx devices with v2.x firmware allow remote attackers to read passwords via a model/__show_info.php?REQUIRE_FILE= absolute path traversal attack, as demonstrated by discovering the admin password.