Link following in Fail2ban

1) Link following

EUVDB-ID: #VU41566

Risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2009-5023

CWE-ID: CWE-59 - Improper Link Resolution Before File Access ('Link Following')

Exploit availability: No

Description

The vulnerability allows a remote non-authenticated attacker to manipulate data.

The (1) dshield.conf, (2) mail-buffered.conf, (3) mynetwatchman.conf, and (4) mynetwatchman.conf actions in action.d/ in Fail2ban before 0.8.5 allows local users to write to arbitrary files via a symlink attack on temporary files with predictable names, as demonstrated by /tmp/fail2ban-mail.txt.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Fail2ban: 0.1.0 - 0.8.3

External links

http://secunia.com/advisories/58841
http://security.gentoo.org/glsa/glsa-201406-03.xml
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=544232
http://github.com/fail2ban/fail2ban/blob/sdist/0.8.5/ChangeLog

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.