Vulnerabilities > CVE-2019-18792 - Code Injection vulnerability in multiple products
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
NONE Integrity impact
PARTIAL Availability impact
PARTIAL Summary
An issue was discovered in Suricata 5.0.0. It is possible to bypass/evade any tcp based signature by overlapping a TCP segment with a fake FIN packet. The fake FIN packet is injected just before the PUSH ACK packet we want to bypass. The PUSH ACK packet (containing the data) will be ignored by Suricata because it overlaps the FIN packet (the sequence and ack number are identical in the two packets). The client will ignore the fake FIN packet because the ACK flag is not set. Both linux and windows clients are ignoring the injected packet.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | 2 | |
| OS | 1 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Leverage Executable Code in Non-Executable Files An attack of this type exploits a system's trust in configuration and resource files, when the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high. The attack can be directed at a client system, such as causing buffer overrun through loading seemingly benign image files, as in Microsoft Security Bulletin MS04-028 where specially crafted JPEG files could cause a buffer overrun once loaded into the browser. Another example targets clients reading pdf files. In this case the attacker simply appends javascript to the end of a legitimate url for a pdf (http://www.gnucitizen.org/blog/danger-danger-danger/) http://path/to/pdf/file.pdf#whatever_name_you_want=javascript:your_code_here The client assumes that they are reading a pdf, but the attacker has modified the resource and loaded executable javascript into the client's browser process. The attack can also target server processes. The attacker edits the resource or configuration file, for example a web.xml file used to configure security permissions for a J2EE app server, adding role name "public" grants all users with the public role the ability to use the administration functionality. The server trusts its configuration file to be correct, but when they are manipulated, the attacker gains full control.
- Manipulating User-Controlled Variables This attack targets user controlled variables (DEBUG=1, PHP Globals, and So Forth). An attacker can override environment variables leveraging user-supplied, untrusted query variables directly used on the application server without any data sanitization. In extreme cases, the attacker can change variables controlling the business logic of the application. For instance, in languages like PHP, a number of poorly set default configurations may allow the user to override variables.
Nessus
| NASL family | Debian Local Security Checks |
| NASL id | DEBIAN_DLA-2087.NASL |
| description | Two vulnerabilities have recently been discovered in the stream-tcp code of the intrusion detection and prevention tool Suricata. CVE-2019-18625 It was possible to bypass/evade any tcp based signature by faking a closed TCP session using an evil server. After the TCP SYN packet, it was possible to inject a RST ACK and a FIN ACK packet with a bad TCP Timestamp option. The client would have ignored the RST ACK and the FIN ACK packets because of the bad TCP Timestamp option. CVE-2019-18792 It was possible to bypass/evade any tcp based signature by overlapping a TCP segment with a fake FIN packet. The fake FIN packet had to be injected just before the PUSH ACK packet we wanted to bypass. The PUSH ACK packet (containing the data) would have been ignored by Suricata because it would have overlapped the FIN packet (the sequence and ack number are identical in the two packets). The client would have ignored the fake FIN packet because the ACK flag would not have been set. For Debian 8 |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 133363 |
| published | 2020-01-31 |
| reporter | This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/133363 |
| title | Debian DLA-2087-1 : suricata security update |
| code | |
References
- https://github.com/OISF/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b
- https://redmine.openinfosecfoundation.org/issues/3324
- https://redmine.openinfosecfoundation.org/issues/3394
- https://github.com/OISF/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006
- https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html