- Threat Encyclopedia
- Malware
- TROJ_ZLOB.FZO
Trojan:Win32/Alureon.CO [Microsoft]; Trojan.Win32.TDSS.chhz [Kaspersky]; Trojan.Gen [Symantec]; DNSChanger.cc [McAfee]; Mal/TDSSPack-AF [Sophos]; Trojan.Win32.FakeSmoke.c [Sunbelt]; Trojan.Win32.Tdss [Ikarus]; Win32/Olmarik.YR trojan [Nod32];
Windows 2000, Windows XP, Windows Server 2003
Dropped by other malware, Downloaded from the Internet
TROJ_ZLOB.FZO can retrieve stored user names and passwords. If successful, the information is send to a specific site, making the network vulnerable to remote attacks.
This Trojan changes the DNS settings of the affected system. As a result, connections from the affected system passes through the attacker's system and enables the attacker to control and monitor communications.
It also monitors Internet browsers to observe search engines. Search results are intercepted by the malware. After a timeout of 10 seconds, the malware changes the search results and redirects users to a random page.
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.
72,192 bytes
EXE
Yes
13 Jan 2010
Compromises system security, Connects to URLs/IPs, Steals information, Terminates processes, Compromises network security
Arrival Details
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Installation
This Trojan drops the following copies of itself into the affected system:
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.
It adds the following mutexes to ensure that only one of its copies runs at any one time:
It injects codes into the following process(es):
Autostart Technique
The scheduled task executes the malware every:
Other System Modifications
This Trojan adds the following registry entries as part of its installation routine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UacDisableNotify = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnableLUA = "0"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%System%\spoolsv.exe = "%System%\spoolsv.exe:*:Enabled:spoolsv.exe"
It modifies the following registry key(s)/entry(ies) as part of its installation routine:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters
NameServer = "{BLOCKED}.162.160,{BLOCKED}.166.191 "
(Note: The default value data of the said registry entry is {user defined}.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters
DhcpNameServer = "{BLOCKED}.162.160,{BLOCKED}.166.191 "
(Note: The default value data of the said registry entry is {user defined}.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters\
Interfaces\{CLSID}
DhcpNameServer = "{BLOCKED}.162.160,{BLOCKED}.166.191 "
(Note: The default value data of the said registry entry is {user defined}.)
Dropping Routine
This Trojan drops the following files:
(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.)
Download Routine
This Trojan downloads an updated copy of itself from the following website(s):
NOTES:
It terminates the processes related to the following:
It uses Simple Object Access Protocol (SOAP) to find the network routers and get the following information:
It accesses the control URL of the router depending on the discovered UPnP device:
It uses brute force to access the routers using the following strings:
[Username]
It can also retrieve stored user names and passwords in by using the CredEnumerateA function and GID abe2869f-9b47-4cd9-a358-c22904dba7f7. If successful, the malware adds an open port and retrieve the external IP address of the router. The information is send to the following site, making the network is vulnerable to remote attacks:
In addition to opening a port in the router, it also changes the DNS settings of the affected system to the following:
It also monitors Internet browsers to observe search engines. Search results are intercepted by the malware. After a timeout of 10 seconds, the malware changes the search results and redirect users to a random page. It monitors the following browsers:
It monitors the following search engines:
It monitors the following URL strings:
9.200
6.766.05
13 Jan 2010
6.767.00
14 Jan 2010
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
Remove malware files dropped/downloaded by TROJ_ZLOB.FZO
Step 3
Restart in Safe Mode
Step 4
Delete this registry value
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
Restore this modified registry value
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 6
To delete the added job file:
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_ZLOB.FZO. 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.