BKDR_AFCORE.NYN
Troj/QakBot-AC (Sophos), Trojan-PSW.Win32.Qbot.ash (Kaspersky)
Windows 2000, XP, Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This backdoor may be downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.
It opens random ports. It executes commands from a remote malicious user, effectively compromising the affected system.
It deletes itself after execution.
TECHNICAL DETAILS
Random TCP ports
Varies
PE
Yes
01 Jan 2011
Compromises system security, Steals information
Arrival Details
This backdoor may be downloaded by other malware/grayware/spyware from remote sites.
It may be unknowingly downloaded by a user while visiting malicious websites.
Installation
This backdoor drops the following component file(s):
- %System%\{random_name 1}.ocx - also detected as BKDR_AFCORE.NYN
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It drops the following non-malicious files:
- %System%\{random_name 1}.dat
- %System%\{random_name 2}.dat
- %System%\{random_name 3}.dat
- %System%\{random_name 4}.dat
- %System%\{random_name 5}.dat
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
Its DLL component is injected to the following process(es):
- explorer.exe
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- GLOBAL/{Random Characters}
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CLASSES_ROOT\CLSID\{random CLSID}\
InprocServer32
@ = %System%\{random_name 1}.ocx
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
ShellIconOverlayIdentifiers\{random_name 1}
@ = {random CLSID}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{random CLSID}\InprocServer32
@ = %System%\{random_name 1}.ocx
Backdoor Routine
This backdoor opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.
It executes the following commands from a remote malicious user:
- ADDTO
- DELCOOKIES
- DELFROM
- DISKFLOOD
- DISKUNFLOOD
- EXPORT
- IPHLP
- LISTCOOKIES
- LSTWND
- MULTICAST
- PERFRM
- RESOLVE
- RESPAWN
- RESTART
- RMOLD
- RUNDLL
- SETCOOKIE
- SETRADIUS
- SETRANGE
- SETSP
- SETSTR
- SETWND
- SHUTDOWN
- SPACE
- STATS
- UNFREEZE
- UNIFORG
- UNINSTALL
Other Details
This backdoor does the following:
- Checks if the following registry key is present upon installation. If not found, it extis from its code and not perform its routines. HKEY_LOCAL_MACHINE\Software\Microsoft\DirectPlay
- Performs the following action after connection is established:
Shut down the machine
Terminate processes
Get IPC, log, and hook timeouts
Open, create and delete files
Initiate distributed denial of service (DDoS) flood attacks
Get system time
Scan logical drives
Shutdown, Restart or Respawn itself - Attempts to resolve the hostname taxfree.{BLOCKED}tplus.net. However, as of this writing, the malware failed to resolve the said hostname.
- Monitors applications(mostly web browsers) such as:
iexplore.exe
firefox.exe
opera.exe
skype.exe - Gathers login information entered in websites with the following strings:
answer
challenge
clave
codigo
cross-border
firma
foreign
identifica
memorable
parol
passphras
password
remittance
s.w.i.f.t
secret
secur
segur
swift
telegraphic
It deletes itself after execution.
SOLUTION
8.900
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
Step 2
Scan your computer with your Trend Micro product and note files detected as BKDR_AFCORE.NYN
Step 3
Restart in Safe Mode
Step 4
Delete the created random CLSID key
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.
Step 5
Delete this registry key
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers\
- {random_name 1}
- {random_name 1}
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_AFCORE.NYN. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.
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