1. Gentoo Linux Security Advisory
| Advisory Reference | GLSA 200710-14 / denyhosts |
| Release Date | October 13, 2007 |
| Latest Revision | October 13, 2007: 01 |
| Impact | normal |
| Exploitable | remote |
| Package | Vulnerable versions | Unaffected versions | Architecture(s) |
| app-admin/denyhosts | < 2.6-r1 | >= 2.6-r1 | All supported architectures |
Related bugreports: #181213
DenyHosts does not correctly parse log entries, potentially causing a remote Denial of Service.
DenyHosts is designed to monitor SSH servers for repeated failed login attempts.
Daniel B. Cid discovered that DenyHosts used an incomplete regular expression to parse failed login attempts, a different issue than GLSA 200701-01.
A remote unauthenticated attacker can add arbitrary hosts into the blacklist, including the "all" keyword, by submitting specially crafted version identification strings to the SSH server banner. An attacker may use this to prevent legitimate users from accessing a host remotely.
There is no known workaround at this time.
All DenyHosts users should upgrade to the latest version:
Code Listing 3.1: Resolution |
# emerge --sync # emerge --ask --oneshot --verbose ">=app-admin/denyhosts-2.6-r1" |