Vulnerabilities > CVE-2017-5566 - Uncontrolled Search Path Element vulnerability in AVG Anti-Virus, Internet Security and Ultimate

047910
CVSS 7.2 - HIGH
Attack vector
LOCAL
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
COMPLETE
Integrity impact
COMPLETE
Availability impact
COMPLETE
local
low complexity
avg
CWE-427

Summary

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.

Vulnerable Configurations

Part Description Count
Application
Avg
3

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Leveraging/Manipulating Configuration File Search Paths
    This attack loads a malicious resource into a program's standard path used to bootstrap and/or provide contextual information for a program like a path variable or classpath. J2EE applications and other component based applications that are built from multiple binaries can have very long list of dependencies to execute. If one of these libraries and/or references is controllable by the attacker then application controls can be circumvented by the attacker. A standard UNIX path looks similar to this If the attacker modifies the path variable to point to a locale that includes malicious resources then the user unwittingly can execute commands on the attackers' behalf: This is a form of usurping control of the program and the attack can be done on the classpath, database resources, or any other resources built from compound parts. At runtime detection and blocking of this attack is nearly impossible, because the configuration allows execution.
  • DLL Search Order Hijacking
    The attacker exploits the functionality of the Windows DLL loader where the process loading the DLL searches for the DLL to be loaded first in the same directory in which the process binary resides and then in other directories (e.g., System32). Exploitation of this preferential search order can allow an attacker to make the loading process load the attackers' rogue DLL rather than the legitimate DLL. For instance, an attacker with access to the file system may place a malicious ntshrui.dll in the C:\Windows directory. This DLL normally resides in the System32 folder. Process explorer.exe which also resides in C:\Windows, upon trying to load the ntshrui.dll from the System32 folder will actually load the DLL supplied by the attacker simply because of the preferential search order. Since the attacker has placed its malicious ntshrui.dll in the same directory as the loading explorer.exe process, the DLL supplied by the attacker will be found first and thus loaded in lieu of the legitimate DLL. Since explorer.exe is loaded during the boot cycle, the attackers' malware is guaranteed to execute. This attack can be leveraged with many different DLLs and with many different loading processes. No forensic trails are left in the system's registry or file system that an incorrect DLL had been loaded.

The Hacker News

idTHN:3EC24BC8841880840FA5C167B0B5E02E
last seen2018-01-27
modified2017-03-22
published2017-03-21
reporterSwati Khandelwal
sourcehttps://thehackernews.com/2017/03/hacking-windows-dll-injection.html
titleUnpatchable 'DoubleAgent' Attack Can Hijack All Windows Versions — Even Your Antivirus!