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Onderwerp: CVS woes: .cvspass

  1. #1
    Chiaki
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    CVS woes: .cvspass

    The file revision control system, CVS,
    stores often used server's password in
    users .cvspass file. (When we use pserver mode to set up a
    central repository and access it from remote workstations,
    that is.)

    The password is "lightly scramblled" for accidental disclosure
    to casual reader, but descrambling it is rather easy.

    Several days ago, I needed to recall the CVS password, but
    I found myself not recalling it since I relied on the automatic
    login by using the password in .cvspass too much.
    So I used the easy descrambling from my own .cvspass file
    under my home directory to recover the password.
    (The same password is used to crypt
    a PDF file by my fellow worker. He remebers the password. A good thing.)

    However, as I recover the password from .cvspass, I found
    one troubling situation.
    When I tried to find how to descramble the lightly
    scrambled password in .cvspass using Google
    (and this was before I check the CVS source file which
    I eventually did and solved my ordeal.)
    I found MANY HITs of people's .cvspass files on the web.
    Theyt contain lightly scramblled passwords.

    Granted that many of these files under user home directories
    visible on the web
    must be the password to be used by anonymous server or
    publicly usable CVS server, but I doubt if ALL of them
    are the result of such benign neglect.

    Is it likely that some .cvspass visible on the web using
    Google search may contain some valuable password to
    a reasonably important server? I think the chances are high. UGH.

    This probably has been a common knowledge among the blackhat community.

    The weak password problem has been discussed often (see the
    relevant two hits from the .cvspass search in google.), but
    having the file published in web and being reported in Google
    is something I didn't expect to see happening.
    No difficult efforts need to be spent to collect .cvspass files.

    URL: Discussions about cvspass. Found in the first page of
    google search for ".cvspass".

    http://www.derkeiler.com/Mailing-Lis...3-05/0073.html

    http://www.contactor.se/~dast/svn/ar...-01/0851.shtml


    --
    int main(void){int j=2003;/*(c)2003 cishikawa. */
    char t[] ="<CI> @abcdefghijklmnopqrstuvwxyz.,\n\"";
    char *i ="g>qtCIuqivb,gCwe\np@.ietCIuqi\"tqkvv is>dnamz";
    while(*i)((j+=strchr(t,*i++)-(int)t),(j%=sizeof t-1),
    (putchar(t[j])));return 0;}/* under GPL */

  2. #2
    Valdis.Kletnieks@vt.edu
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    Re: CVS woes: .cvspass

    --==_Exmh_-1914559229P
    Content-Type: text/plain; charset=us-ascii

    On Tue, 27 Jul 2004 03:00:52 +0900, Chiaki <ishikawa@yk.rim.or.jp> said:

    > Granted that many of these files under user home directories
    > visible on the web
    > must be the password to be used by anonymous server or
    > publicly usable CVS server, but I doubt if ALL of them
    > are the result of such benign neglect.


    If a user's home directory is visible via a web browser, the .cvspass
    is probably not the biggest problem....

    --==_Exmh_-1914559229P
    Content-Type: application/pgp-signature

    -----BEGIN PGP SIGNATURE-----
    Version: GnuPG v1.2.4 (GNU/Linux)
    Comment: Exmh version 2.5 07/13/2001

    iD8DBQFBBpzFcC3lWbTT17ARAvHFAJ9dcDz3OG/g2Urk/+bIdT5AJAOtswCg0epY
    laObpTWaF6jfGYt9IOJ+dS8=
    =Cuex
    -----END PGP SIGNATURE-----

    --==_Exmh_-1914559229P--

  3. #3
    Greg A. Woods
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    Re: CVS woes: .cvspass

    [ On Tuesday, July 27, 2004 at 03:00:52 (+0900), Chiaki wrote: ]
    > Subject: CVS woes: .cvspass
    >
    > The file revision control system, CVS,
    > stores often used server's password in
    > users .cvspass file. (When we use pserver mode to set up a
    > central repository and access it from remote workstations,
    > that is.)


    Anyone using the CVS pserver mechanism for anything other than totally
    anonymous access gets only what they deserve.

    If you want to keep your CVS repository secure then don't try to use CVS
    as a security tool -- it wasn't designed for it, and it cannot be
    "fixed" either (it's not a bug -- CVS is a version control tool, not a
    security tool and CVS is designed _only_ to be executed by the unique
    user performing operations on repository).

    Use SSH or some other secure remote job execution tool to create a
    secure connection for CVS to work with.

    --
    Greg A. Woods

    +1 416 218-0098 VE3TCP RoboHack <woods@robohack.ca>
    Planix, Inc. <woods@planix.com> Secrets of the Weird <woods@weird.com>

  4. #4
    Andreas Beck
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    Re: CVS woes: .cvspass

    Valdis.Kletnieks@vt.edu wrote:
    > On Tue, 27 Jul 2004 03:00:52 +0900, Chiaki <ishikawa@yk.rim.or.jp> said:
    > > Granted that many of these files under user home directories
    > > visible on the web
    > > must be the password to be used by anonymous server or
    > > publicly usable CVS server, but I doubt if ALL of them
    > > are the result of such benign neglect.

    > If a user's home directory is visible via a web browser, the .cvspass
    > is probably not the biggest problem....


    It looks like quite some people check the .cvspass into cvs itself. When
    doing a quick check of yesterdays advisory, most hits were from
    cvs-viewing utilities.

    Maybe they just don't know what .cvspass is for and think "oh, there's a
    ..cvs in there, I'd better check it in". Of course this doesn't explain
    why they move it into the respective directory in the first place, as
    it usually resides in $HOME, while CVS sources usually create their own
    directory on checkout.

    Also note, that for exploitation you do not even need to reverse the
    password. You just add the .cvspass entries to your own .cvspass and
    get access.


    Kind regards,

    Andreas Beck

    --
    Andreas Beck
    http://www.bedatec.de/

  5. #5
    Delian Krustev
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    Re: CVS woes: .cvspass

    On Tuesday 27 July 2004 23:20, Greg A. Woods wrote:
    > Anyone using the CVS pserver mechanism for anything other than totally
    > anonymous access gets only what they deserve.


    brr, do not forget that the security might be guaranteed on different
    layers. E.g. ipsec secures the insecure protocols(the ones that transfer
    data in plain text or with weak encryption), such as telnet or cvs
    with pserver.


  6. #6
    Greg A. Woods
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    Re: CVS woes: .cvspass

    [ On Thursday, August 5, 2004 at 12:52:10 (+0300), Delian Krustev wrote: ]
    > Subject: Re: CVS woes: .cvspass
    >
    > On Wednesday 04 August 2004 23:35, Greg A. Woods wrote:
    > > Nope, sorry, but that's just not possible, at least not with CVS pserver.

    >
    > What's not possible ? Using IPSEC ?!


    It's not possible to "secure" CVSpserver using IPsec. Period.

    I.e. it's just not logically possible, using CVSpserver, do do what you
    said could be done. To do so violates the fundamental security model of
    CVS and the Unix(like) systems it runs upon.

    IPsec can only secure the inter-host network links and thus make it
    possible to securely use CVS via remote job protocols such as RSH (which
    use host-level security techniques and assume their virtual circuits are
    already secure) instead of requriring SSH. IPsec does not operate at
    the user level and even if it did you'd still require unique system
    identities for every individual human user.

    Note that even pushing the IPsec implementation away from the host
    kernel and onto a gateway router implies blindly accepting many more
    assumptions about the security of the local area network.


    > I'm not sure what You mean by "human user".


    The whole point of security, i.e. authentication, authorisation, and
    accountability, is to relate all internal system activity back to real,
    verified, authorised, individual human users.

    I use the common phrase "human user" to differentiate the real people
    who use a system from the identities they assume, or rather are given,
    inside of a computing system environment.

    It is fundamental that each system account be used by one and only one
    unique human user. Without this condition accountability is impossible
    (at least for the users of that shared user-ID) unless it's provided by
    some external means (e.g. a security guard at the door of the
    Tempest-level room where the computer is located who is instructed to
    securely record every access to the computer, and who is capable of
    securely performing this duty).

    It is also fundamental that every system activity performed by a human
    user be performed using a unique-per-human _system_ level identity. If
    you do not meet this condition then you are violating the fundamental
    security model of the system and all bets are off, all warrantees null
    and void, etc.

    (note that a single human individual can assume multiple system
    identities without compromising accountability -- it's only not secure
    to have multiple humans assume a single system identity)


    > The users in cvs doesn't have
    > to be mapped to system users(CVSROOT/passwd).


    That's true at some level, but it's a (common) fallacy as well, and it
    begins with a faulty foundation from the get go.

    CVS only works securely with real, individual, unique-per-human, system
    level user-IDs, and where the CVS processes on the server run using the
    system identity of the human user they are acting on behalf of.

    If your human users are not using unique internal _system_ level
    representations of their unique identities then you have no secure
    ground to stand on in the first place.

    I.e. the mere concept of using cvspserver (and thus CVSROOT/passwd) is a
    non-starter if you are worried in any way about the security of your CVS
    repository. CVS users (the real humans using CVS) _MUST_ use unique
    system user identities in order that you can even begin to consider the
    state of the security of your CVS repository. CVSROOT/passwd entries do
    not equate to real system identities even if they map identically to
    real system identities because use of CVSROOT/passwd in that way implies
    running CVS as root and that's not secure in any way whatsoever
    (i.e. not by design and not by implementation).

    There are no if's, and's, or but's about it -- this is really _really_
    fundamental computer security basics. CVS security, by design and by
    the way CVS is implemented, relies _entirely_ on system security and
    unique system level identities. Running CVS as root, or having all CVS
    users access one system account by way of CVSpserver with CVS running as
    that one system account, leaves CVS without any secure accountability
    whatsoever, while at the same time providing numerous holes big enough
    for CVS users to drive big Mac trucks through at each other, if not
    indeed also through to root level compromises in the former scenario.

    Like I'm sure I've said many times before, CVSpserver should never ever
    be used for anything but totally anonymous (and presumably read-only)
    access to a CVS repository, and hopefully that pserver accessible
    repostitory is also only an untrusted copy of the real CVS repository
    that the developers have write access to, and hopefully the system it
    runs on has the sole purpose of providing anonymous pserver access, or
    at least the identity it runs under is totally untrusted within that
    system.

    Let me say it again the other way around for the benefit of clarity:

    Only ever use CVSpserver for totally _anonymous_ access.


    > There's a site outhere. It's sf.net . They demonstrate, with the number
    > of projects being hosted there (with pserver access), You're not right
    > again.


    They demonstrate nothing of the sort (at least not with their CVSpserver
    offering).

    In the scenario you speak of sf.net has no real requirement for
    accountability -- their offerning using CVSpserver is effectively the
    same as providing anonymous access. Sf.net doesn't care who the real
    humans are in this case -- they simply do their best (which isn't always
    perfect) to keep whole projects from interfering with each other. (and
    their none-too-rare failings have been directly attributable to this
    particular mis-use of CVS -- i.e. their "lame" attempt to use CVS as
    part of their security infrastructure)

    Meanwhile, IIUC, sf.net does also offer secure SSH access to systems
    hosting CVS repositories and they use true system identities for eash
    SSH account, and presumably with this offering there's normally one (or
    maybe more) unique system accounts for every real human using this
    service, though of course the responsibility of verifying the uniqueness
    of system identities will be on the shoulders of the CVS project admins,
    and perhaps not on sf.net themselves. I.e. if two human users share an
    account there's only their peers within their project to account to and
    sf.net only attempts to provide the minimum level of _system_ security
    necessary for their users to police each other.

    Either way sf.net is a big enough target that if they have not
    implemented their services securely and within the security model
    provided by their underlying systems then we'll likely hear about the
    result here in this forum.

    > On the other side, people's stupidity is endless. I won't be surprised
    > to see private keys posted in a public forum. This, ofcourse, could
    > be nothing but a reason for admiration.


    No disagreement there! :-)

    --
    Greg A. Woods

    +1 416 218-0098 VE3TCP RoboHack <woods@robohack.ca>
    Planix, Inc. <woods@planix.com> Secrets of the Weird <woods@weird.com>

  7. #7
    Delian Krustev
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    Re: CVS woes: .cvspass

    On Wednesday 04 August 2004 23:35, Greg A. Woods wrote:
    > Nope, sorry, but that's just not possible, at least not with CVS pserve=

    r.

    What's not possible ? Using IPSEC ?!

    > The unix security model, within which CVS is designed and implemented t=

    o
    > work, _requires_ unique user-IDs for each and every unique human user.
    >
    > This is in fact a basic, fundamental, requirement of all systems of thi=

    s
    > type.
    >


    I'm not sure what You mean by "human user". The users in cvs doesn't have
    to be mapped to system users(CVSROOT/passwd).

    > CVS is not, and cannot be, a security tool so running it as root and
    > pretending to have it do all your authentication and authorisation flie=

    s
    > directly in the face of the underlying system security model and leaves
    > you with no real and verifiable accountability whatsoever, and it also
    > leaves you open to the possibility of yet another vulnerability vector
    > in the form of the unaudited CVS code base. Remember that the vast
    > majority of all security incidents originate internally to the
    > organisations they affect.


    You're right CVS is not a security tool. It's a version control system.
    In fact, what You are talking about ? Do You remember what the subject
    of the post You're replying to was ?

    [snip]

    > If you think your network is secure enough courtesy other mechanisms
    > then you can use RSH instead of SSH, but DO NOT try to use cvspserver
    > for anything but totally anonymous access.


    There's a site outhere. It's sf.net . They demonstrate, with the number
    of projects being hosted there (with pserver access), You're not right
    again.

    The cvs server doesn't have to be run as root. IMHO it's pretty bad
    idea to run it as root. Furthermore cvs provides several hooks, which
    could be utilized if you need control at certain points and over
    certain operations. E.g. commiters could be controlled by module and
    branch.

    About the password scrambling. It's well documented why it's like
    that. The scrambling algorithm is also described. And it's all there.
    In the manual.=20
    S.O. said that fake security is worse than no security. Password=20
    encryption in .cvspass should be considered "no security".


    On the other side, people's stupidity is endless. I won't be surprised
    to see private keys posted in a public forum. This, ofcourse, could
    be nothing but a reason for admiration.

  8. #8
    Andy Dustman
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    Re: CVS woes: .cvspass

    On Thu, 5 Aug 2004 12:52:10 +0300, Delian Krustev <krustev@krustev.net> wrote:
    > On Wednesday 04 August 2004 23:35, Greg A. Woods wrote:


    > > If you think your network is secure enough courtesy other mechanisms
    > > then you can use RSH instead of SSH, but DO NOT try to use cvspserver
    > > for anything but totally anonymous access.

    >
    > There's a site outhere. It's sf.net . They demonstrate, with the number
    > of projects being hosted there (with pserver access), You're not right
    > again.


    SourceForge only allows anonymous CVS access through pserver.
    Read-write access is through SSH only.

  9. #9
    Delian Krustev
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    Re: CVS woes: .cvspass

    Your mails are getting longer and longer. Please try saying more
    in less words next time. Thank You.

    On Thursday 05 August 2004 23:11, Greg A. Woods wrote:
    > It's not possible to "secure" CVSpserver using IPsec. Period.
    >
    > I.e. it's just not logically possible, using CVSpserver, do do what you
    > said could be done. To do so violates the fundamental security model o=

    f
    > CVS and the Unix(like) systems it runs upon.


    There's nothing like "fundamental security model". Not in unix/linux, nor
    in CVS. I suppose You're talking about UID/GID based security.

    I'll repeat myself. Security could be guaranteed on different layers.
    In the software case - operating system, application, components, etc ..

    Please tell me what, from the things I've said, is not "logically possibl=
    e"
    to be done and I'll provide an example.

    > IPsec can only secure the inter-host network links and thus make it
    > possible to securely use CVS via remote job protocols such as RSH (whic=

    h
    > use host-level security techniques and assume their virtual circuits ar=

    e
    > already secure) instead of requriring SSH. IPsec does not operate at
    > the user level and even if it did ..


    <bold>
    >.. you'd still require unique system
    > identities for every individual human user.

    </bold>

    The local access to the repository requires each commiter to have direct
    r/w access to each of the directories inside the repository. This gives
    him the power to compromise it in anyway he likes. The commits performed
    by locally executed cvs command are performed by creating/renaming/unlink=
    ing
    files.

    > Note that even pushing the IPsec implementation away from the host
    > kernel and onto a gateway router implies blindly accepting many more
    > assumptions about the security of the local area network.


    The keyword here is opportunistic encryption. The nodes of trust
    will be the server, the client and the client's DNS provider. The third
    one could be eliminated. No lan security is involved in that scenario.

    > The whole point of security, i.e. authentication, authorisation, and
    > accountability, is to relate all internal system activity back to real,
    > verified, authorised, individual human users.
    >
    > I use the common phrase "human user" to differentiate the real people
    > who use a system from the identities they assume, or rather are given,
    > inside of a computing system environment.
    >
    > It is fundamental that each system account be used by one and only one
    > unique human user. Without this condition accountability is impossible
    > (at least for the users of that shared user-ID) unless it's provided by
    > some external means (e.g. a security guard at the door of the
    > Tempest-level room where the computer is located who is instructed to
    > securely record every access to the computer, and who is capable of
    > securely performing this duty).


    Not right. The services are virtulized nowadays. Each one could provide
    it's own privilege/accounting methods(guaranteed on application layer).

    > It is also fundamental that every system activity performed by a human
    > user be performed using a unique-per-human _system_ level identity. If
    > you do not meet this condition then you are violating the fundamental
    > security model of the system and all bets are off, all warrantees null
    > and void, etc.


    No "fundamental security model". Nothing to break.

    [snip]

    There's nothing concreete in your words. All you're talking about
    is fundamental principles. That makes me think You've never managed
    a single cvs repository.

  10. #10
    Greg A. Woods
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    Re: CVS woes: .cvspass

    [ On Friday, August 6, 2004 at 19:27:57 (+0300), Delian Krustev wrote: ]
    > Subject: Re: CVS woes: .cvspass
    >
    > Your mails are getting longer and longer. Please try saying more
    > in less words next time. Thank You.


    Unfortunately it seems I have to be very careful and very explicit with
    my words or else you evidently misunderstand what I am trying to say. :-)

    I.e. the more words I use the less likely you are to misinterpret them,
    assuming you do read them all quite carefully. ;-)


    > There's nothing like "fundamental security model". Not in unix/linux, nor
    > in CVS. I suppose You're talking about UID/GID based security.


    I'm talking about _the_ fundamental security model of unix(like)
    systems. And there certainly is one -- it's quite well known and very
    well documented, completely with a patent that's been signed over to the
    public domain.

    I don't know what _you_ might mean by the phrase "UID/GID based
    security". I'm talking about the basic concepts of computing system
    security and network security and how they relate to implementing a
    secure CVS repository on a unix(like) system with network client/server
    access.


    > I'll repeat myself. Security could be guaranteed on different layers.


    No, I'm sorry but you're still very wrong in this case. As I've already
    tried to say two different ways already it is simply not possible to
    guarantee any security whatsoever for a CVS repository using CVSpserver
    by piling together different, dis-contiguous, dis-connected layers of
    security on top of it. What you have proposed directly violates the,
    basic, fundamental, underlying security model of all unix(like) systems.
    You will be left with no accountability whatsoever.

    IPsec can only be used to protect virtual circuts that might happen to
    have to travel over insecure networks. However IPsec does not, and by
    design cannot, have any part to play in the user-level security required
    for implementing a secure CVS repository. Even using host-based IPsec
    and making the assumption that each user can be uniquely identified by
    the client host he or she is connecting from there's still no
    accountability for those user's actions on the server side when some
    poor afterthought of a hack like CVSpserver is used.

    SSH can also be used to provide the same level of protection, with the
    added fact that SSH integrates directly into the security model of the
    underlying system and thus no other security mechanisms such as those
    used by RSH are needed to use SSH with CVS (or rather SSH already
    incorporates those security mechanisms within itself). However SSH
    relies on the fact that in a secure environment every user will have a
    unique system identity just as would be done if CVS were used on a
    standalone non-networked secure multi-user system.


    > The local access to the repository requires each commiter to have direct
    > r/w access to each of the directories inside the repository. This gives
    > him the power to compromise it in anyway he likes. The commits performed
    > by locally executed cvs command are performed by creating/renaming/unlinking
    > files.


    Hmmm.... what you've said suggests that you need to go back and try to
    understand the basic underlying security model of the system that CVS
    was designed and implemented to run on top of before you consider the
    implications of what I'm trying to say.

    Note further that this model I'm talking about applies to many similar
    applications, including but not limited in any way to other file-based
    version control systems such as RCS, SCCS, TCCS, Aegis, and so on.

    Indeed as you say local access to the repository is required for each
    CVS user.

    In some scenarios it would indeed be easy for an authorised user to go
    in and mess about direclty with the repository files in order to
    compromise them. However the potential for compromise that you speak of
    is mitigated almost entirely by the nature of the application and how it
    is used. It is after all in fact the goal of CVS to provide mediated,
    shared, access to the common repository files. I won't go into how this
    mitigation works as all that's important in this discussion is to point
    out that it's not relevant to why IPsec does not, and cannot, do what
    you suggest.

    What this means though is that CVS, by design and by its implementation,
    relies _entirely_ on the underlying operating system for all of its
    security.

    As you hint CVS is no different in how it must be viewed from a security
    perspective than any text editor or compiler or spreadsheet calculator.
    CVS cannot safely be made responsible for the security of the repository
    any more than a text editor could be -- yet that is exactly what the
    CVSpserver hack attempts to do. Any and all ways of using CVSpserver
    try to turn CVS into the security application that it was not designed
    to be.

    Something like IPsec can only be used to provide security for the
    inter-host connections that might be used to interact with a CVS
    repository -- IPsec does not, and cannot, make something like CVSpserver
    into a security application.


    There's also a very blatant fact of history to consider:

    The evidence of CVS' failings as a security application have been
    splattered all over this very forum only quite recently, and it should
    be clear to anyone experienced with security software who has taken even
    a casual look inside of CVS that those previous compromises I refer to
    are only the tip of the inevitable and proverbial iceberg that anyone
    (mis)using CVSpserver is guaranteed to eventually run square into. CVS
    simply cannot ever be a safe part of any security infrastructure or
    application. It was not designed to do this and it was certainly not
    implemented to do this. Any and all attempts to use CVSpserver and/or
    other hastily cobbled together security hacks on top of the basic CVS
    code are bound to fail, sometimes catastrophically, and no amount of
    tweaking or auditing the CVS code will ever remove these risks
    sufficiently for such use.

    CVSpserver cannot, and must not under any circumstances, regardless of
    whether IPsec or similar is used with it, be used for anything but
    totally anonymous access to a copy of a CVS repository.

    Would you make your text editor responsible for authenticating and
    authorizing user accesses and accounting for their actions? Do you
    think IPsec could somehow make it safe to do this with your text editor?

    --
    Greg A. Woods

    +1 416 218-0098 VE3TCP RoboHack <woods@robohack.ca>
    Planix, Inc. <woods@planix.com> Secrets of the Weird <woods@weird.com>

  11. #11
    Robin Rosenberg
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    Re: CVS woes: .cvspass

    On Wednesday 04 August 2004 22.35, Greg A. Woods wrote:
    > [ On Thursday, July 29, 2004 at 16:30:07 (+0300), Delian Krustev wrote: ]
    >
    > > Subject: Re: CVS woes: .cvspass
    > >
    > > On Tuesday 27 July 2004 23:20, Greg A. Woods wrote:
    > > > Anyone using the CVS pserver mechanism for anything other than totally
    > > > anonymous access gets only what they deserve.

    > >
    > > brr, do not forget that the security might be guaranteed on different
    > > layers. E.g. ipsec secures the insecure protocols(the ones that transfer
    > > data in plain text or with weak encryption), such as telnet or cvs
    > > with pserver.

    >
    > Nope, sorry, but that's just not possible, at least not with CVS pserver.
    >
    > The unix security model, within which CVS is designed and implemented to
    > work, _requires_ unique user-IDs for each and every unique human user.

    [...]
    > CVS is not, and cannot be, a security tool so running it as root and
    > pretending to have it do all your authentication and authorisation flies


    "pretending"?

    With 1.12 CVS can (and that seems to be the default) use system
    authentication methods like PAM and does setuid etc before doing any cvs
    operations, which takes places as the respective user. It won't even let
    me add users in CVSROOT/passwd. It does allow me to set a different password
    for CVS acess though.

    But also 1.11 did setuid etc before doing CVS operations and perhaps earlier
    versions also, but I'm not sure about that.

    -- robin


  12. #12
    Robin Rosenberg
    CVS woes: .cvspass
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    Re: CVS woes: .cvspass

    On Wednesday 04 August 2004 22.35, Greg A. Woods wrote:
    > [ On Thursday, July 29, 2004 at 16:30:07 (+0300), Delian Krustev wrote: ]
    >
    > > Subject: Re: CVS woes: .cvspass
    > >
    > > On Tuesday 27 July 2004 23:20, Greg A. Woods wrote:
    > > > Anyone using the CVS pserver mechanism for anything other than totally
    > > > anonymous access gets only what they deserve.

    > >
    > > brr, do not forget that the security might be guaranteed on different
    > > layers. E.g. ipsec secures the insecure protocols(the ones that transfer
    > > data in plain text or with weak encryption), such as telnet or cvs
    > > with pserver.

    >
    > Nope, sorry, but that's just not possible, at least not with CVS pserver.
    >
    > The unix security model, within which CVS is designed and implemented to
    > work, _requires_ unique user-IDs for each and every unique human user.
    >
    > This is in fact a basic, fundamental, requirement of all systems of this
    > type.
    >
    > CVS is not, and cannot be, a security tool so running it as root and
    > pretending to have it do all your authentication and authorisation flies
    > directly in the face of the underlying system security model and leaves
    > you with no real and verifiable accountability whatsoever, and it also
    > leaves you open to the possibility of yet another vulnerability vector
    > in the form of the unaudited CVS code base. Remember that the vast
    > majority of all security incidents originate internally to the
    > organisations they affect.


    With 1.12 CVS can (and that seems to be the default) use system
    authentication methods like PAM and does setuid etc before doing any cvs
    operations, which takes places as the respective user. It won't even let
    me add users in CVSROOT/passwd. It does allow me to set a different password
    for CVS acess though.

    But also 1.11 did setuid etc before doing CVS operations.

    -- robin

  13. #13
    Tilman Schmidt
    CVS woes: .cvspass
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    Re: CVS woes: .cvspass

    This is a multi-part message in MIME format...

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    Greg A. Woods schrieb in <bugtraq@SecurityFocus.com>:
    > [ On Thursday, August 5, 2004 at 12:52:10 (+0300), Delian Krustev wrote: ]
    >
    >> There's a site outhere. It's sf.net . They demonstrate, with the number
    >> of projects being hosted there (with pserver access), You're not right
    >> again.


    > In the scenario you speak of sf.net has no real requirement for
    > accountability -- their offerning using CVSpserver is effectively the
    > same as providing anonymous access. Sf.net doesn't care who the real
    > humans are in this case -- they simply do their best (which isn't always
    > perfect) to keep whole projects from interfering with each other.


    In fact, you are even more right than you seem to think. Sf.net's
    pserver access is actually anonymous and read-only. Project data in
    the SF repository is considered public, and open to anonymous read
    access anyway. Their pserver access doesn't add anything to that.

    > Meanwhile, IIUC, sf.net does also offer secure SSH access to systems
    > hosting CVS repositories and they use true system identities for eash
    > SSH account, and presumably with this offering there's normally one (or
    > maybe more) unique system accounts for every real human using this


    That is so, and SSH access, with a system identity that is a member
    of the project's development team, is required for committing changes
    to a project repository.

    > service, though of course the responsibility of verifying the uniqueness
    > of system identities will be on the shoulders of the CVS project admins,
    > and perhaps not on sf.net themselves.


    Indeed. The registration form asks you to enter a real name, and
    a valid E-mail address which is verified by a confirmation E-mail,
    but there is no verification beyond that.

    --
    Tilman Schmidt E-Mail: Tilman.Schmidt@ePost.de
    Bonn, Germany
    Diese Nachricht besteht zu 100% aus wiederverwerteten Bits.
    Ungeöffnet mindestens haltbar bis: (siehe Rückseite)

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