CVE-2017-5566 in Ultimate
Summary
by MITRE
Code injection vulnerability in AVG Ultimate 17.1 (and earlier), AVG Internet Security 17.1 (and earlier), and AVG AntiVirus FREE 17.1 (and earlier) allows a local attacker to bypass a self-protection mechanism, inject arbitrary code, and take full control of any AVG 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.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/26/2024
The CVE-2017-5566 vulnerability represents a critical code injection flaw affecting multiple AVG security products including AVG Ultimate, Internet Security, and AntiVirus FREE versions 17.1 and earlier. This vulnerability stems from a fundamental design flaw in how these security applications implement their self-protection mechanisms, creating a pathway for local attackers to execute arbitrary code within the context of AVG processes. The attack vector specifically exploits the absence of Protected Processes feature in these products, which normally would prevent unauthorized modifications to critical system components. The vulnerability operates through what is commonly referred to as a "DoubleAgent" attack pattern, where an attacker leverages the registry modification capabilities to inject malicious code into legitimate processes.
The technical implementation of this vulnerability involves exploiting the Image File Execution Options (IFEO) registry key, which is typically used for debugging and profiling applications. AVG products implement a self-protection mechanism designed to prevent local processes from modifying IFEO settings for security applications, thereby protecting against common code injection techniques. However, the flaw lies in the implementation of this protection mechanism itself, which can be circumvented through a sophisticated renaming attack. Attackers can temporarily rename the IFEO registry keys during the attack window, effectively bypassing the self-protection checks that are supposed to prevent unauthorized modifications. This technique allows attackers to inject arbitrary Application Verifier Provider DLLs, which are then loaded by the AVG processes during normal execution flows, providing complete code execution privileges.
From an operational perspective, this vulnerability represents a severe compromise of the security model underlying these antivirus products. The attack requires local system access but provides attackers with the ability to escalate privileges and execute code within the context of high-privilege AVG processes, potentially leading to complete system compromise. The vulnerability affects the core protection mechanisms that users rely on to secure their systems, making it particularly dangerous in enterprise environments where these products are widely deployed. The attack is especially concerning because it targets the very security software designed to protect against such threats, creating a paradoxical situation where the protection mechanism itself becomes the attack surface. The impact extends beyond simple code injection to potential privilege escalation, data exfiltration, and persistent backdoor establishment within infected systems.
The vulnerability aligns with several common attack patterns documented in the ATT&CK framework, particularly those related to process injection and privilege escalation techniques. It also maps to CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-94, which covers improper control of generation of code. The attack methodology demonstrates how attackers can exploit legitimate system features for malicious purposes, making detection and prevention particularly challenging. Organizations should implement immediate mitigations including updating to patched versions of AVG products, monitoring registry modifications related to IFEO keys, and implementing additional endpoint protection measures. The vulnerability underscores the importance of robust process protection mechanisms and the necessity of regularly updating security software to address emerging threats. Security professionals should also consider implementing registry monitoring solutions and privileged access management controls to detect and prevent similar exploitation attempts against other security products.