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Report
CIAC A-03
_______________________________________________________________________
THE COMPUTER INCIDENT ADVISORY CAPABILITY (CIAC) ADVISORY NOTICE
_______________________________________________________________________
Tools available to check the spread of the "WANK" Worm
October 20, 1989 1130 PST Number A-3
Summary
This is a follow-up bulletin to the CIAC advisory notice A-2 dated
October 16, 1989, stating that the "WANK" worm is attacking HEPnet and
the NASA SPAN network on VAX/VMS systems connected via DECnet. Our
latest information is that approximately 60 to 70 systems, mostly at
non-DOE sites, have been infected. The rate at which this worm is
spreading seems to be slowing, although more detailed information about
the spread of this worm is not currently available.
CIAC now has additional information about the "WANK" computer worm
outbreak. The worm targets VMS machines, and can only be propagated
via DECnet. The worm exploits well known security holes within the
DECnet/VMS system in order to propagate itself. However, most DOE
sites have not yet been affected. In order to help prevent your site
>from becoming infected, we recommend that you follow procedures
described in this bulletin , and use a tool to check your VAX/VMS
systems for the same weaknesses the worm exploits. We also are
providing you with a list of the worm symptoms, as well as a tool to
kill the worm if your systems become infected.
If your site is infected, or if you have any questions, please contact
CIAC. CIAC phone numbers and addresses appear at the end of this
notice.
Advisory Notice
A computer worm written in DCL for DEC-VMS has been attacking the
HEPnet and the NASA SPAN networks. This worm can only be propagated
via DECnet. The primary methods of attack include a brute force attack
on passwords as well as exploiting well known security vulnerabilities
of DECnet/VMS. One vulnerability is the default DECnet account, which
is a facility for users who do not have a specific login ID for a
machine and want some degree of anonymous access. It uses the default
DECnet account to copy itself to a machine, and then uses the "TASK 0"
and Submit/Remote features of DECnet to invoke the remote copy. Once
the worm has successfully penetrated a system, it will infect .COM
files and create new security vulnerabilities. It then broadcasts
these vulnerabilities to another machine. It may also damage files or
crash systems.
In our last memo we published an analysis of the worm by Kevin
Oberman. That analysis contained a error that we would like to
correct. In that notice we printed the quote:
4. Information on the password used to access the system is mailed to
the user GEMTOP on SPAN node 6.59. Some versions may have a different
address.
The actual user is "GEMPAK" not "GEMTOP".
Visible Symptoms
The following information is an extract from a report by John McMahon
on detecting the symptoms of the WANK worm. This information was
compiled after a thorough analysis of copies of various versions of
the WANK worm retrieved from different infected sites. There are
indications that these copies were derived from three different
"starter" versions of the worm. The worm is self-modifying, and may
also have been manually modified by others. There may also be other
currently undetected versions of the worm with additional
capabilities.
Specifically, some or all of the following symptoms have been noted on
infected systems:
1) Account passwords have been changed without the knowledge of the
user, or the system manager.
2) Processes are running on your system with the process name NETW_nnnn
(where nnnn is a random number). Check this with the SHOW SYSTEM
command.
3) Command procedures/data file names starting with one or two letters
and up to a five digit number appear in the SYS$LOGIN: directory of an
account. Examples: C12345.COM, A7007.DAT.
Note: Earlier reports that the file W.COM is created by the worm
appear to be in error. Any "anti-worm" procedure involving the
creation of a blank W.COM;32767 will NOT stop the worm.
4) The SYS$ANNOUNCE message, prior to the USERNAME: login prompt, has
been
redefined to the following WANK logo.
W O R M S A G A I N S T N U C L E A R K I L L E R S
_______________________________________________________________
\__ ____________ _____ ________ ____ ____ __ _____/
\ \ \ /\ / / / /\ \ | \ \ | | | | / / /
\ \ \ / \ / / / /__\ \ | |\ \ | | | |/ / /
\ \ \/ /\ \/ / / ______ \ | | \ \| | | |\ \ /
\_\ /__\ /____/ /______\ \____| |__\ | |____| |_\ \_/
\___________________________________________________/
\ /
\ Your System Has Been Officically WANKed /
\_____________________________________________/
You talk of times of peace for all, and then prepare for war.
5) The SYSTEM account can no longer receive mail. The DISMAIL flag has
been set in SYSTEM's UAF record.
6) Users log into the system and report that all of their files have
been deleted while logging in. The user observes many %DELETE-I-FILDEL
messages ,and DIRECTORY reports that no files are found. The system
manager follows up on this report and finds the files are still there,
and that the system login procedure (SYLOGIN, SYS$SYLOGIN) has been
modified.
Note: Earlier reports that the worm performs mass deletion of files
appears to be in error.
7) Command procedures have been modified with code to reactivate the
FIELD account if the person running the procedure has SYSPRV.
8) A remote DECnet site contacts you about odd VAXPhone call messages
coming from your node. The VAXPhone ring messages do not contain a
userid, but a strange "fortune cookie" saying.
Note: the node id can be found in the NETSERVER.LOG files in your
DECnet default account. [CIAC note]: Please note the node number of
the system that sent you the message and pass that information to your
respective network security manager, or CIAC so that the infected node
can be informed.
9) Top-level directories have had their OWNER protection field changed
to O:RWED.
10) A remote DECnet site contacts you about logfails (on several
accounts) on the remote site which were traced back to an account on
your machine. Similarly, a remote site contacts you because a local
account tried to read the SYSUAF/RIGHTSLIST files on the remote node.
Regardless of whether or not you think you have been infected,
download the ANTIWANK.COM command procedure and start it running on
your node immediately. This program will kill copies of the worm that
are running on your node.
You may see the whole list of symptoms and recommended fixes by
obtaining the file WORM-INFO.COM. See details below.
Procedures to stop the spread of this worm
CIAC recommends that you use the following procedures, quoted from a
message by Ron Tencati (SPAN Security Manager), to stop the spread of
the WANK worm:
1) It is IMPERATIVE that all systems protect or remove the DECnet TASK
0 object to prevent reoccurrence of this worm, OR MORE SERIOUS ATTACKS
OF THIS KIND IN THE FUTURE!
The TASK object can be secured by either of the following methods:
Method 1)
Issue the command:
NCP> CLEAR OBJECT TASK ALL
after the network is started up. This command can also be
inserted into the procedure SYSTARTUP>COM (SYSTARTUP_V5.COM on
V5.x systems) after the call to STARTNET.COM. In addition
which the system is running, this command must be executed EACH
TIME the network is restarted.
Method 2:
Issue the following commands ONCE:
NCP> SET OBJECT TASK USER DECNET PASSWORD <a bunch of garbage>
NCP> DEFINE OBJECT TASK USER DECNET PASSWORD <a bunch of
garbage>
This causes a login failure to be generated whenever the TASK
object is accessed. Once done, this change will be permanent.
NOTE We have received one report that TASK 0 is
required for DECwindows. Read your documentation!
2) Under NO circumstances it is acceptable for an account to have a
password the same as the username. Passwords (passPHRASES) should be
created so that they are difficult to guess, multi- word phrases are
preferable. As a precaution, we recommend that all passwords be
changed. Additionally, system managers may choose to revalidate ALL
accounts.
If a system had the DECNET TASK 0 protected as above, the DECNET
account protected against SUBMIT/REMOTE (described below) and no user
had their userid as their password, it was immune to this WORM. As a
result, the number of nodes actually INFECTED by this attack is
relatively small. The number ATTACKED however, is large.
3. NETWORK ATTACKS
To protect against the SUBMIT/REMOTE attack, run AUTHORIZE and make
sure that all network account flags are set to NOBATCH, NODIALUP,
NOLOCAL, and NOREMOTE.
4. FIELD ACCOUNT
Make sure the FIELD ACCOUNT does not have the password FIELD. DISUSER
the account. You must SEARCH all .COM files for a
"field/remote/dialup." If the search shows it is in .COM files, They
have a trojan horse appended to the files. When the .COM file is
executed, This Trojan horse will try to reset account FIELD to
/NODISUSER and password to FIELD. You should either delete the
corrupted .COM file and obtain a good one elsewhere, or examine the
file and remove the affected lines of the command procedure.
5. WORM FILES
The WORM source files are W.COM or a single alphabetic character (C or
D) followed by 4 or 5 numeric characters. (Cnnnnn.COM), ("nnnn"
represents a random number). The WORM will start a process or
processes running. These processes are named in format NETW_nnnn, and
should be deleted. PHONE_nnnn may also be running as the WORM utilizes
the PHONE object in an attempt to send a message to a user on another
randomly selected node.
6. ALARMS
Some alarms generated by the WORM are related to PHONE.EXE and
FAL.EXE. The majority of the alarms are login failures as the WORM
attempts to log into specific accounts.
We recommend that alarms be set immediately for logins, logouts,
breakin attempts, modifications to the system and net UAF's, and to
changes to user and system passwords.
Tools available
A series of tools are available to control the WANK worm. These may be
obtained by anonymous FTP access from node ROGUE.LLNL.GOV
(128.115.2.99). They may also be obtained from SPAN and ESnet. Contact
CIAC for more information.
[.SECURITY]CHECK_SYSTEM.COM, written by Kevin Oberman, will check your
entire system for the security holes used by the WANK worm. It then
reports back all system problems so that they can be corrected.
DEC has provided a fix for the well known problem with the default
DECnet account hole called SYS$UPDATE:NETCONFIG_UPDATE.COM for VMS
V5.2. It is available from the VMS V5.2 distribution tape. If you
have this, CIAC recommends that you run it now. If you donUt have
access or are running an earlier system such as V4., you may obtain
>from ROGUE.LLNL.GOV a program called: FIX-FAL.COM which fixes the
default DECnet account.
The program by John McMahon can be obtained by downloading
ANTIWANK.COM. This program kills the worm processes. You can also run
it as a vaccine even if your systems have not been infected.
WORM-INFO.TXT contains an important report by John McMahon . It
contains a list of symptoms, recommended proceduresand the code for
ANTIWANK.COM.
If your site has been infected, or if you have any questions, please
contact either of the following CIAC team members:
David Brown, (415) 423-9878 or FTS 543-9878
Gene Schultz, (415) 422-8193 or FTS 532-8193
or send electronic mail to:ciac@tiger.llnl.gov
CIAC FAX: (415) 422-4294 FTS 532-4294
