Code injection vulnerability in Avast Premier 12.3 (and earlier), Internet Security 12.3 (and earlier), Pro Antivirus 12.3 (and earlier), and Free Antivirus 12.3 (and earlier) allows a local attacker to bypass a self-protection mechanism, inject arbitrary code, and take full control of any Avast process via a "DoubleAgent" attack. One perspective on this issue is that (1) these products do not use the Protected Processes feature, and therefore an attacker can enter an arbitrary Application Verifier Provider DLL under Image File Execution Options in the registry; (2) the self-protection mechanism is intended to block all local processes (regardless of privileges) from modifying Image File Execution Options for these products; and (3) this mechanism can be bypassed by an attacker who temporarily renames Image File Execution Options during the attack.

Avast Internet Security v11.x.x, Pro Antivirus v11.x.x, Premier v11.x.x, Free Antivirus v11.x.x, Business Security v11.x.x, Endpoint Protection v8.x.x, Endpoint Protection Plus v8.x.x, Endpoint Protection Suite v8.x.x, Endpoint Protection Suite Plus v8.x.x, File Server Security v8.x.x, and Email Server Security v8.x.x allow attackers to bypass the DeepScreen feature via a DeviceIoControl call.

Heap-based buffer overflow in the Avast virtualization driver (aswSnx.sys) in Avast Internet Security, Pro Antivirus, Premier, and Free Antivirus before 11.1.2253 allows local users to gain privileges via a Unicode file path in an IOCTL request.

The Antivirus Free (aka com.zrgiu.antivirus) application 7.2.16.02 for Android does not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.

The Zoner AntiVirus Free application for Android does not verify that the server hostname matches a domain name in the subject's Common Name (CN) field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate, as demonstrated by a server used for updating virus signature files.

Untrusted search path vulnerability in avast! Free Antivirus version 5.0.594 and earlier allows local users, and possibly remote attackers, to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse mfc90loc.dll that is located in the same folder as an avast license (.avastlic) file.