Patchwork D8353: debugcommands: create new debugantivirusrunning command

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Submitter phabricator
Date April 1, 2020, 2:47 p.m.
Message ID <differential-rev-PHID-DREV-ykuwhajlqcate46534nk-req@mercurial-scm.org>
Download mbox | patch
Permalink /patch/45958/
State New
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phabricator - April 1, 2020, 2:47 p.m.
durin42 created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  This writes the EICAR test file to .hg/cache, in an attempt to trigger
  an AV scanner's scanning engine. This should let us (in theory) detect
  some cases when a user's slowness is a result of AV scanning.

REPOSITORY
  rHG Mercurial

BRANCH
  default

REVISION DETAIL
  https://phab.mercurial-scm.org/D8353

AFFECTED FILES
  mercurial/debugcommands.py

CHANGE DETAILS




To: durin42, #hg-reviewers
Cc: mercurial-devel
phabricator - April 2, 2020, 12:33 a.m.
indygreg added a comment.


  I do not understand what the intended side-effect of running this command is supposed to be.

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To: durin42, #hg-reviewers
Cc: indygreg, mercurial-devel
phabricator - April 2, 2020, 3:04 p.m.
durin42 added a comment.


  In D8353#124864 <https://phab.mercurial-scm.org/D8353#124864>, @indygreg wrote:
  
  > I do not understand what the intended side-effect of running this command is supposed to be.
  
  Well, if an AV engine isn't configured to ignore the user's clone, then this will enrage the AV engine by writing out a "virus".
  
  This started out as a joke, but I kind of came around to the realization that it could be useful. So I'm like....90% sure I think this patch makes sense. :)

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To: durin42, #hg-reviewers
Cc: indygreg, mercurial-devel
phabricator - April 2, 2020, 6:50 p.m.
mharbison72 added a comment.


  Should it delete the file after writing it, or don't bother because the AV may have it locked?

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To: durin42, #hg-reviewers
Cc: mharbison72, indygreg, mercurial-devel
phabricator - April 2, 2020, 6:51 p.m.
durin42 added a comment.


  In D8353#124948 <https://phab.mercurial-scm.org/D8353#124948>, @mharbison72 wrote:
  
  > Should it delete the file after writing it, or don't bother because the AV may have it locked?
  
  I figured just leave it since it's tiny, but maybe we should sleep for a while and then remove it?

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To: durin42, #hg-reviewers
Cc: mharbison72, indygreg, mercurial-devel
phabricator - April 3, 2020, 4:25 a.m.
mharbison72 added a comment.


  In D8353#124949 <https://phab.mercurial-scm.org/D8353#124949>, @durin42 wrote:
  
  > In D8353#124948 <https://phab.mercurial-scm.org/D8353#124948>, @mharbison72 wrote:
  >
  >> Should it delete the file after writing it, or don't bother because the AV may have it locked?
  >
  > I figured just leave it since it's tiny, but maybe we should sleep for a while and then remove it?
  
  That might work.  I don't feel too strongly about it, but it seemed weird to leave junk in there and I only realized why as I was writing out the comment.  The couple of times I've worked on viruses that evaded detection, file names are what I keyed in on.

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To: durin42, #hg-reviewers
Cc: mharbison72, indygreg, mercurial-devel
phabricator - April 17, 2020, 6:28 p.m.
marmoute added a comment.


  Silly question, could make anti virus cough on the mercurial source itself?

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To: durin42, #hg-reviewers
Cc: marmoute, mharbison72, indygreg, mercurial-devel
phabricator - April 17, 2020, 6:28 p.m.
marmoute added inline comments.

INLINE COMMENTS

> debugcommands.py:135-138
> +            util.b85decode(
> +                b'ST#=}P$fV?P+K%yP+C|uG$>GBDK|qyDK~v2MM*<JQY}+dK~6+LQba95P'
> +                b'E<)&Nm5l)EmTEQR4qnHOhq9iNGnJx'
> +            )

I think it could be useful to have a clarification of this payload is from an inline comment.

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To: durin42, #hg-reviewers
Cc: marmoute, mharbison72, indygreg, mercurial-devel
phabricator - April 17, 2020, 6:58 p.m.
durin42 added a comment.


  I don't think so, since it's base85-armored and my understanding is that really it's only supposed to trigger in isolation...

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To: durin42, #hg-reviewers
Cc: marmoute, mharbison72, indygreg, mercurial-devel
phabricator - April 20, 2020, 9:15 a.m.
This revision now requires changes to proceed.
marmoute added a comment.
marmoute requested changes to this revision.


  The approach seems good, but extra comment and cleanup would be nice.

INLINE COMMENTS

> debugcommands.py:139
> +            )
> +        )
> +

As @mharbison72 pointed out, it would be nicer to remove the file after it has been scanned.

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To: durin42, #hg-reviewers, marmoute
Cc: marmoute, mharbison72, indygreg, mercurial-devel
phabricator - June 8, 2020, 5:43 p.m.
marmoute added a comment.
marmoute accepted this revision.


  Seems overall good. I have some fear over the `sleep` usage, butit does not seems to depends on test, and I don't know what antivirus looks like.

INLINE COMMENTS

> debugcommands.py:143
> +    # Give an AV engine time to scan the file.
> +    time.sleep(2)
> +    util.unlink(repo.cachevfs.join('eicar-test-file.com'))

That seems short ? that might fails on heavy load system. Also, this confused me a bit. How is the antivirus failure supposed to manifest when this code is run? I have no experience with them.

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To: durin42, #hg-reviewers, marmoute
Cc: mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel
phabricator - June 9, 2020, 8:48 p.m.
durin42 added a comment.


  Best guess (given I've never hit an AV problem) is that the AV engine would lose its lunch on the EICAR file and alert the user. I figure if the AV engine isn't picking up on it after 2 seconds then it's probably also not a performance issue for us.

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To: durin42, #hg-reviewers, marmoute
Cc: mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel
phabricator - June 10, 2020, 9:19 a.m.
marmoute added a comment.


  My main question here is : what does "AV engine would lose its lunch" translate in terms of the python runtime ?

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To: durin42, #hg-reviewers, marmoute
Cc: mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel
phabricator - June 10, 2020, 2:32 p.m.
durin42 added a comment.


  Sadly  I have no idea on that.

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To: durin42, #hg-reviewers, marmoute
Cc: mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel
phabricator - June 10, 2020, 2:50 p.m.
marmoute added a comment.


  In D8353#128838 <https://phab.mercurial-scm.org/D8353#128838>, @durin42 wrote:
  
  > Sadly  I have no idea on that.
  
  Do we have a poor windows user that could serve an a guinea pig here ?

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To: durin42, #hg-reviewers, marmoute
Cc: mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel
phabricator - June 29, 2020, 8:48 a.m.
pulkit added a comment.


  In D8353#128839 <https://phab.mercurial-scm.org/D8353#128839>, @marmoute wrote:
  
  > In D8353#128838 <https://phab.mercurial-scm.org/D8353#128838>, @durin42 wrote:
  >
  >> Sadly  I have no idea on that.
  >
  > Do we have a poor windows user that could serve an a guinea pig here ?
  
  Seems like we are not able to find a guinea pig here. How about pushing the patch and finding one in wild? :D

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To: durin42, #hg-reviewers, marmoute
Cc: pulkit, mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel
phabricator - June 29, 2020, 10:58 p.m.
khanchi97 added a comment.


  In D8353#129493 <https://phab.mercurial-scm.org/D8353#129493>, @pulkit wrote:
  
  > In D8353#128839 <https://phab.mercurial-scm.org/D8353#128839>, @marmoute wrote:
  >
  >> In D8353#128838 <https://phab.mercurial-scm.org/D8353#128838>, @durin42 wrote:
  >>
  >>> Sadly  I have no idea on that.
  >>
  >> Do we have a poor windows user that could serve an a guinea pig here ?
  >
  > Seems like we are not able to find a guinea pig here. How about pushing the patch and finding one in wild? :D
  
  Sounds good to me.

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To: durin42, #hg-reviewers, marmoute
Cc: khanchi97, pulkit, mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel
phabricator - July 7, 2020, 6:20 p.m.
pulkit added a comment.


  I will go ahead and push it before upcoming rc if I hear no objections.

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To: durin42, #hg-reviewers, marmoute
Cc: khanchi97, pulkit, mercurial-patches, marmoute, mharbison72, indygreg, mercurial-devel

Patch

diff --git a/mercurial/debugcommands.py b/mercurial/debugcommands.py
--- a/mercurial/debugcommands.py
+++ b/mercurial/debugcommands.py
@@ -127,6 +127,18 @@ 
     ui.write(b'%d:%s\n' % (r.rev(a), hex(a)))
 
 
+@command(b'debugantivirusrunning', [])
+def debugantivirusrunning(ui, repo):
+    """attempt to trigger an antivirus scanner to see if one is active"""
+    with repo.cachevfs.open('eicar-test-file.com', b'wb') as f:
+        f.write(
+            util.b85decode(
+                b'ST#=}P$fV?P+K%yP+C|uG$>GBDK|qyDK~v2MM*<JQY}+dK~6+LQba95P'
+                b'E<)&Nm5l)EmTEQR4qnHOhq9iNGnJx'
+            )
+        )
+
+
 @command(b'debugapplystreamclonebundle', [], b'FILE')
 def debugapplystreamclonebundle(ui, repo, fname):
     """apply a stream clone bundle file"""