Use-after-free in Apache HTTP Server

1) Use-after-free

EUVDB-ID: #VU8504

Risk: Low

CVSSv3.1: 5.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N/E:F/RL:O/RC:C]

CVE-ID: CVE-2017-9798

CWE-ID: CWE-416 - Use After Free

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to obtain potentially sensitive information.

The vulnerability exists due to use-after-free error when processing HTTP OPTIONS requests in server/core.c, when limits are configured in .htaccess or httpd.conf configuration files. A remote unauthenticated attacker can read portions of memory through HTTP OPTIONS requests and gain access to potentially sensitive data.

The vulnerability is dubbed Optionsbleed.

Mitigation

Update to version 2.4.28.
http://www.apache.org/dist/httpd/CHANGES_2.4.28

Vulnerable software versions

Apache HTTP Server: 2.2.0 - 2.4.27

External links

http://svn.apache.org/viewvc?view=revision&revision=1807655 
http://github.com/hannob/optionsbleed
http://openwall.com/lists/oss-security/2017/09/18/2
http://blog.fuzzing-project.org/60-Optionsbleed-HTTP-OPTIONS-method-can-leak-Apaches-server-memory....
http://www.apache.org/dist/httpd/CHANGES_2.4.28

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. However, a fully functional exploit for this vulnerability is available.