Cve 2003 0352 Ms03026 Rpc Computer Science Essay

CVE-2003-0352, is a exposure uses Remote Procedure Calls, which is an built-in constituent of Windows runing system. The RPC provides inter-process communicating mechanism which allows plans on one computing machine to seamlessly put to death codification on distant systems. This Windows RPC was derived from Open Software Foundation ( OSF ) RPC with some extra Microsoft specific extensions.

The exposure uses this RPC protocol to work the distant system and derive entree to put to death assorted codification on the exploited machine. The peculiar exposure affects the Distributed Component Object Model ( DCOM ) interface with RPC, which listens on RPC enabled TCP ports, because of the consequence of the wrong handling of deformed RPC messages packages exchanged over TCP/IP. This causes the interface passing DCOM object activation petitions over RPC on the waiter to non work decently, leting the aggressor to run code Local System privileges on an affected system leting the aggressor to take any action on the system, including put ining plans, sing altering or canceling informations, or making new histories with full privileges.

How exploit plants

The exploit uses the Windowss RPC to derive entree on the mark machine, windows does RPC utilizing NetBIOS protocol. Window uses three ports for NetBIOS they are 135, 139 and 445, NetBIOS works utilizing both TCP and UDP protocols over IP. The CVE-2003-0352 exposure merely effects the TCP protocol when utilizing RPC for initialising DCOM objects, doing a Buffer flood and deriving entree to the mark computing machine. Buffer Overflow is to seek to hive away more informations in a buffer so its allocated memory, if the application fails to look into the buffer and executes the codification in the buffer this codes is executed at the application privileges by the operating system at that place by doing any assorted codification to be executed that had overflowed the buffer. In some instances a buffer overflow pests application to crash non leting any more of its services.

HRESULT CoGetInstanceFromFile (


CLSID * pclsid,

IUnknown * punkOuter,

DWORD dwClsCtx,

DWORD grfMode,

OLECHAR * szName,

ULONG cmq,

MULTI_QI * rgmqResults

) ;

Code CoGetInstanceFromFile Syntax

The feat usage “ CoGetInstanceFromFile ” method to make the buffer flood and addition entree. This is done by utilizing the ‘szName ‘ parametric quantity of the method which is the file name to initialise the DCOM object with.

CoGetInstanceFromFile (






L ” Degree centigrade: 1234561111111111111111111111111.doc ” ,


& A ; qi ) ;

Code Sample Function Call

When the files name is excessively long, it would do a local buffer flood. “ GetPathForServer ” method is used for acquiring the way of a file from the waiter but the map merely supports a maximal file size of 0x220, this is what is used by the feat to do the flood by gowning over the size. However if we use the Windowss provided API to do it can non be done as it cheque of the size before go oning any farther, this prevents us for utilizing this exploit locally. The exploit uses this map through RPC by building a deformed package doing the buffer overflow possible, because after the client transmits the parametric quantities for the method to the waiter, it is translated as “ servernamec $ 1234561111111111111111111111111.doc ” . Here the waiter does non look into the length of the ‘szName ‘ parametric quantity and merely look into for the waiter name where it allocates the buffer of 0x20 merely because, NetBIOS upper limit name length at that place by leting us to work.

Now we know where the buffer flood is present and how it ‘s being exploited. The feat still needs to put to death assorted codification on the waiter, this is done by utilizing the “ leap to register ” technique allows for dependable development of stack buffer overflows without the demand for excess room for a NOP-sled and without holding to think stack beginnings, which uses the JMP ESP leap. This is done by doing the plan to name “ DbgPrint ” method, because the JMP ESP is executed before naming this method. Then the flood occurs the application throws the exclusion which is handled utilizing the replace Structured Exception Handling ( SHE ) , thereby naming “ DbgPrint ” method. The exploit changes the ESP registry value before doing the exclusion at that place by airting the plan executing to a known memory beginning, in this instance it ‘s redirected to an beginning where shell codification is present and is executed. The shell codification here in the feat is to open a connexion onto another system at that place by supplying a distant terminus to the distant machine for put to deathing bids.

The executing of the feat can be divided into the undermentioned four phases

Establish a connexion to NETBIOS port of the targeted system.

Send the deformed NetBIOS RPC petition for the file name that is longer than 0x20 in length

When the operating system executes the codification in overflow it opens a port on the petition machine through which we can entree the terminus.

Access and put to death bids through the connected shell on the victims system.

Degree of Impact

CVE-2003-0352 has a CVSS base mark of 7.5 which puts it in a HIGH hazard. The exposure has a high degree of security menace on the accomplished system. The CVSS Base mark is provided by CVE which is determined by CVSS ( Common Vulnerability Scoring System ) criterions. Depending on this mark each CVE is been divided into one of the three types HIGH ( CVSS base mark of scope 7.0 to 10.0 ) , MEDIUM ( CVSS base mark of scope 4.0 to 6.9 ) and LOW ( CVSS base mark of scope 0.0 to 3.9 ) ( CERT ) .

And Microsoft has besides stated the Maximum Severity Rating is critical, as the exposure has the ability to run the codification of aggressor ‘s pick.

After Effectss on the System

The exposure causes a immense consequence on the system as it allows the aggressor to put to death any application as a local user which causes critical harm, as they might derive entree to the user restricted files and services. If the aggressor was able to obtain decision maker privileges so he can wholly take of the system doing informations loss and other sorts of rational belongings harm. And besides the consequence of the exposure is on many Microsoft Windows Operating system version virus and warms use the victims systems to distribute them self ‘s over. Such the Blaster/MSblast/LovSAN and Nachi/Welchia worms which were able successfully used the feat to distribute and take over other systems.

Scale and range of the exposure

We can state that the graduated table of spreading of the exposure is rather big as it attempts Microsoft Windows NT 4.0 / 4.0 Terminal Services Edition, Windows 2000, Windows XP and Windows Server 2003 which have the most portion of operating system used. And the besides with the usage of the exposure the aggressor is able to take maximal control of the victims computing machines creates a grate range of utilizing the exposure to work. The working the exposure is besides non that hard as it is with others this besides increase the range of doing utilizing exposure by many people.

Remedial Action for bar for acquiring exploited

To work this exposure, the aggressor would necessitate the ability to direct a specially crafted petition to port 135, 139, 445 or 593 or any other specifically configured RPC port on the distant machine. For intranet environments, these ports would usually be accessible, but for Internet connected machines, these would usually be blocked by a firewall. In the instance where these ports are non blocked, or in an intranet constellation, the aggressor would non necessitate any extra privileges.

Best patterns recommend barricading all TCP/IP ports that are non really being used and most firewalls including the Windows Internet Connection Firewall ( ICF ) block those ports by default. For this ground, most machines attached to the Internet should hold RPC over TCP or UDP blocked. RPC over UDP or TCP is non intended to be used in hostile environments such as the Internet. More robust protocols such as RPC over HTTP are provided for hostile environments.

And besides to most of import mitigate is to maintain our system updated which helps protect from this exposure ‘s. Depending on the system we are utilizing it is truly of import to look into the appropriate spot released by Microsoft Corporation. This spot will supply sufficient security to avoid buffer flood.

As an option for any ground the system is non updated to piece so the system is vulnerable in order to protect it from onslaught it is necessary to disenable DCOM services on the host. Even though it disable the ability of that system to pass on with other systems on the web it is of import to protect from onslaught.


As we have seen from the above subdivision how the exploit work we can state that the exposure possess a high degree of menace for the exploited system. And besides Microsoft has rated the exposure as critical because when exploited proves unrestricted to put to death codification with local privileges which might eventual escalate to the coup d’etat of the hole system. In instance of a web if the aggressor was able to work the Primary Domain Controller ( PDC ) , the aggressor has the ability to take over the complete sphere, create users or alter their privileges doing a major security of the full sphere itself.

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