ALIASES:

Sirefef, Zeroaccess, Kazy, Conjar, ZAccess, Zacess

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

ZEROACCESS, also known as ZACCESS, refers to a family of rootkits often found bundled with other malware, most of which belong to the FAKEAV malware family.

ZEROACCESS disables anti-malware products on the affected system. While most malware families with the same capability rely on disabling anti-malware services and processes, ZEROACCESS modifies the access control list (ACL) of the affected system. This routine ensures that anti-malware programs will not run on the affected system, which opens the system to further malware infection.

ZEROACCESS may download other malware families onto affected systems. They also hijack Internet traffic and search engine results to display advertisements and generate Web redirections to malicious websites.

Later variants of this malware family employ Domain Generation Algorithm (DGA) routines to contact its C&C server. This behavior makes it difficult to block the malicious server since the domain is generated randomly.

  TECHNICAL DETAILS

Payload: Downloads files

Installation

This backdoor drops the following files:

  • %Application Data%\8c0f0459\@
  • %Application Data%\8c0f0459\X
  • %Windows%\1493438348

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)

It creates the following folders:

  • %Application Data%\8c0f0459
  • %Application Data%\8c0f0459\U

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\8c0f0459
ImagePath = "\systemroot\1493438348:1945172902.exe"

It adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "%Application Data%\8c0f0459\X"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\Interface\{b1041c7f-46ea-d87c-4a51-abba7b80f3da}

HKEY_CLASSES_ROOT\Software\8c0f0459

It adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\Interface\{b1041c7f-46ea-d87c-4a51-abba7b80f3da}
u = "dword:00000075"

HKEY_CLASSES_ROOT\Interface\{b1041c7f-46ea-d87c-4a51-abba7b80f3da}
cid = "{hex values}"

HKEY_CURRENT_USER\Software\8c0f0459
u = "dword:00000075"

HKEY_CURRENT_USER\Software\8c0f0459
id = "{hex values}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\explorer.exe = "%Windows%\explorer.exe:*:Enabled:Windows Explorer"

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}ie.cn

Related Malware

Related Web Attack