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Thread: Unknown svchost.exe DNS port 53 network activity

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  1. #1
    Raffi Guest

    Unknown svchost.exe DNS port 53 network activity

    First off sorry for cross posting. I'm not sure what this is although
    it resembles a trojan.

    I noticed heavy activity on my router as well as my workstation LAN
    connection icon in the tray. After some digging appears to be a svchost
    process that is listening on port 53 with a remote address of my ISP's
    DNS server. My router is not set to forward DNS traffic to a specific
    system.

    I have run the following without any success in catching this bug

    AntiVir antivirus
    Avast antivirus
    Spybot S&D
    Ad Aware
    AVG antispyware

    I got the following information for the related process from Port
    Explorer

    Command line: c:\windows\system32\svchost.exe -k Network Service

    Any help in identifying this bug and cleaning will be greatly
    appreciated.

    Thanks,
    Raffi


  2. #2
    jmatt@webace.com.au Guest

    Re: Unknown svchost.exe DNS port 53 network activity

    Raffi wrote:
    After some digging appears to be a svchost
    > process that is listening on port 53 with a remote address of my ISP's
    > DNS server.


    svchost port 53

    http://www.google.com.au/search?hl=e...e+Search&meta=


  3. #3
    David H. Lipman Guest

    Re: Unknown svchost.exe DNS port 53 network activity

    From: "Raffi" <thegrizzzly@yahoo.com>

    | First off sorry for cross posting. I'm not sure what this is although
    | it resembles a trojan.
    |
    | I noticed heavy activity on my router as well as my workstation LAN
    | connection icon in the tray. After some digging appears to be a svchost
    | process that is listening on port 53 with a remote address of my ISP's
    | DNS server. My router is not set to forward DNS traffic to a specific
    | system.
    |
    | I have run the following without any success in catching this bug
    |
    | AntiVir antivirus
    | Avast antivirus
    | Spybot S&D
    | Ad Aware
    | AVG antispyware
    |
    | I got the following information for the related process from Port
    | Explorer
    |
    | Command line: c:\windows\system32\svchost.exe -k Network Service
    |
    | Any help in identifying this bug and cleaning will be greatly
    | appreciated.
    |
    | Thanks,
    | Raffi

    Yaeh exxcessive Cross-Posting for Domain Name Resolution !

    Unless you can prove that there is something causing DNS calls outside your ISP Domain, this
    is NORMAL.

    --
    Dave
    http://www.claymania.com/removal-trojan-adware.html
    http://www.ik-cs.com/got-a-virus.htm



  4. #4
    Raffi Guest

    Re: Unknown svchost.exe DNS port 53 network activity


    David H. Lipman wrote:
    > From: "Raffi" <thegrizzzly@yahoo.com>
    >
    > | First off sorry for cross posting. I'm not sure what this is although
    > | it resembles a trojan.
    > |
    > | I noticed heavy activity on my router as well as my workstation LAN
    > | connection icon in the tray. After some digging appears to be a svchost
    > | process that is listening on port 53 with a remote address of my ISP's
    > | DNS server. My router is not set to forward DNS traffic to a specific
    > | system.
    > |
    > | I have run the following without any success in catching this bug
    > |
    > | AntiVir antivirus
    > | Avast antivirus
    > | Spybot S&D
    > | Ad Aware
    > | AVG antispyware
    > |
    > | I got the following information for the related process from Port
    > | Explorer
    > |
    > | Command line: c:\windows\system32\svchost.exe -k Network Service
    > |
    > | Any help in identifying this bug and cleaning will be greatly
    > | appreciated.
    > |
    > | Thanks,
    > | Raffi
    >
    > Yaeh exxcessive Cross-Posting for Domain Name Resolution !
    >
    > Unless you can prove that there is something causing DNS calls outside your ISP Domain, this
    > is NORMAL.
    >
    > --
    > Dave
    > http://www.claymania.com/removal-trojan-adware.html
    > http://www.ik-cs.com/got-a-virus.htm


    It turns out it wasn't normal. I had recently installed a P2P program
    on my PC and it had added a ton of entries in my hosts file. I'm
    surprised none of the spyware programs gave me even the slightest
    warning about these entries.

    Raffi


  5. #5
    David H. Lipman Guest

    Re: Unknown svchost.exe DNS port 53 network activity

    From: "Raffi" <thegrizzzly@yahoo.com>


    | It turns out it wasn't normal. I had recently installed a P2P program
    | on my PC and it had added a ton of entries in my hosts file. I'm
    | surprised none of the spyware programs gave me even the slightest
    | warning about these entries.
    |
    | Raffi

    Still normal. The ONLY way this would be abnormal is if a DNSChanger Trojan was installed
    and the PC was NOT using the ISP provided DNS servers but a tainted, malicious, set of DNS
    servers.

    Now having entries .\etc\hosts file will circumvent DNS calls. Based upon a Registry
    setting that sets the order of name to address resolution, first the OS calls the hosts
    files and if a name to IP address is listed the IP address of the .\etc\hosts table will be
    used. If a name (alias) is not in that hosts table then the TCP/.IP stack will cause a DNS
    call to a DNS server which will then return the IP address.

    The way you have your original post worded SVCHOST was found to communicate with your ISP's
    DNS server.

    One can only go by the wording of your original post and p\based upon what I read, I saw no
    normality. While having modifications to the hosts table can be indicative of malicious
    software, that is NOT always true. The owner/operator can apply the MVP Hosts file to their
    computer to block malicious sites and the application is not malicious. If you can post
    actuall FireWall logs of DNS activitry, Netstat dumps and the whol or extracts of the hosts
    table, one can make a more definite determination of malware.

    --
    Dave
    http://www.claymania.com/removal-trojan-adware.html
    http://www.ik-cs.com/got-a-virus.htm



  6. #6
    Raffi Guest

    Re: Unknown svchost.exe DNS port 53 network activity


    David H. Lipman wrote:
    > From: "Raffi" <thegrizzzly@yahoo.com>
    >
    >
    > | It turns out it wasn't normal. I had recently installed a P2P program
    > | on my PC and it had added a ton of entries in my hosts file. I'm
    > | surprised none of the spyware programs gave me even the slightest
    > | warning about these entries.
    > |
    > | Raffi
    >
    > Still normal. The ONLY way this would be abnormal is if a DNSChanger Trojan was installed
    > and the PC was NOT using the ISP provided DNS servers but a tainted, malicious, set of DNS
    > servers.
    >
    > Now having entries .\etc\hosts file will circumvent DNS calls. Based upon a Registry
    > setting that sets the order of name to address resolution, first the OS calls the hosts
    > files and if a name to IP address is listed the IP address of the .\etc\hosts table will be
    > used. If a name (alias) is not in that hosts table then the TCP/.IP stack will cause a DNS
    > call to a DNS server which will then return the IP address.
    >
    > The way you have your original post worded SVCHOST was found to communicate with your ISP's
    > DNS server.
    >
    > One can only go by the wording of your original post and p\based upon what I read, I saw no
    > normality. While having modifications to the hosts table can be indicative of malicious
    > software, that is NOT always true. The owner/operator can apply the MVP Hosts file to their
    > computer to block malicious sites and the application is not malicious. If you can post
    > actuall FireWall logs of DNS activitry, Netstat dumps and the whol or extracts of the hosts
    > table, one can make a more definite determination of malware.
    >
    > --
    > Dave
    > http://www.claymania.com/removal-trojan-adware.html
    > http://www.ik-cs.com/got-a-virus.htm


    Thanks for the reply. Removing the P2P software and clearing the
    \etc\hosts file did not correct the issue after all. I just logged in
    with the administrator account and the network activity is no longer
    there. This seems to be happenning only when I log into my personal
    account. During my last login, SERVICES.EXE was making the connections
    rather than SVCHOST.EXE. Is there a way to determine if these files
    have been tampered with?

    I'll try to get more information from netstat etc.

    Raffi


  7. #7
    David H. Lipman Guest

    Re: Unknown svchost.exe DNS port 53 network activity

    From: "Raffi" <thegrizzzly@yahoo.com>

    |
    | Thanks for the reply. Removing the P2P software and clearing the
    | \etc\hosts file did not correct the issue after all. I just logged in
    | with the administrator account and the network activity is no longer
    | there. This seems to be happenning only when I log into my personal
    | account. During my last login, SERVICES.EXE was making the connections
    | rather than SVCHOST.EXE. Is there a way to determine if these files
    | have been tampered with?
    |
    | I'll try to get more information from netstat etc.
    |
    | Raffi

    Yes. Download and use Process Explorer
    http://www.microsoft.com/technet/sys...sExplorer.mspx

    And look at not only the file name SERVICES.EXE but the fully qualified name and path.

    SERVICES.EXE and SVCHOST.EXE should ONLY be executed from the folder; %windir%\system32
    If they are executed from any other location it is a sure sign of malware.

    Also, there are DLLs that can be loaded and use SERVICES.EXE and SVCHOST.EXE such that the
    legitimate SERVICES.EXE and/or SVCHOST.EXE are being loaded and used but are loading
    malicuious DLL files.

    You can also run MSCONFIG.EXE and compare what is loaded as administrator vs. what is loaded
    in you everyday account. You indicated the activity stopped when you logged on as admin.
    thus what may be loaded to cause the activity is being loaded by that personal account.

    --
    Dave
    http://www.claymania.com/removal-trojan-adware.html
    http://www.ik-cs.com/got-a-virus.htm



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