Pierluigi Paganini July 30, 2014

Joxean Koret, a security researcher at Singapore-based consultancy COSEINC, has publicly revealed a series of flaws which affect major antivirus engines.

The security researcher at Singapore-based consultancy COSEINC, Joxean Koret, has discovered different flaws in 14 of 17 major antivirus engines. The researcher has presented the results of his study (PDF) at the recent SyScan 360 security conference in Beijing this month. Koret explained how he had used a custom fuzzing suite to discover exploitable local and remote flaws in popular antivirus engines, the list of affected products is long and includes solutions offered by vendors such as Avast, AVG, Avira, Bitdefender, Comodo, DrWeb, ESET, F-Prot, F-Secure and Panda.

The antivirus engine is the core of any antivirus solution, different engines are used by multiple products, for example BitDefender is the most widely used antivirus kernel (e.g. G-Data, eScan, F-Secure).

As illustrated by Koret in his presentation different anti-virus software offer too much administrator privilege that could be exploited by an attacker to conduct man-in-the-middle (MiTM).

“AV engines makes your computer more vulnerable with a varying degree of performance penalty. The AV engine is as vulnerable to zero day attacks as the applications it tries to protect from.” is reported in the presentation.

“If the application is local: your local attack surface increased. If the application is remote: your remote attack surface increased. If your application runs with the highest privileges, installs kernel drivers, a packet filter and tries to handle anything your computer may do…Your attack surface dramatically increased.”

The principal flaws discovered by the researcher are buffer and heap overflow vulnerabilities, local escalation of privileges and file format bugs. Many of the vulnerabilities disclosed are “nothing new”, but anyway we can consider this presentation as the first time a researcher had publicly revealed such extensive faults affecting major anti-virus engines.

The court explained that HTTP connections, ordinarily used for updates represents one of the most concerning security issues, due the lack of proper validation mechanisms, the expert also revealed that major vendors often fail to review their code.

“If one can MITM the connection (for example, in a LAN) one can install new files and/or replace existing installation files. It often translates in completely owning the machine with the AV engine installed as updates are not commonly signed. Yes. They aren’t”