[VulnWatch] ekg insecure temporary file creation and arbitrary code execution

From: ZATAZ Audits (exploits_at_zataz.net)
Date: 07/05/05

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    Date: Tue, 05 Jul 2005 08:51:07 +0200
    To: vuldb@securityfocus.com, vuln@secunia.com, vuln@k-otik.com, moderators@osvdb.org, bugs@securitytracker.com, submissions@packetstormsecurity.org, news@securiteam.com, xforce@iss.net, bugtraq@securityfocus.com, vulnwatch@vulnwatch.org, full-disclosure@lists.grok.org.uk
    
    

    #########################################################

    ekg insecure temporary file creation and arbitrary code execution

    Vendor: http://dev.null.pl/ekg/
    Advisory: http://www.zataz.net/adviso/ekg-06062005.txt
    Vendor informed: yes
    Exploit available: no
    Impact : high
    Exploitation : high

    #########################################################

    The vulnerabilities are caused due to temporary file being created
    insecurely.
    This can be exploited via symlink attacks in combination to create and
    overwrite
    arbitrary files with the privileges of the user running the affected
    script and
    also arbitrary command possible by spiking the temporary file.

    ##########
    Versions:
    ##########

    ekg <= 2005-06-05 22:03

    ##########
    Solution:
    ##########

    For the symlink attack use kernel patch such as grsecurity

    #########
    Timeline:
    #########

    Discovered : 2005-05-27
    Vendor notified : 2005-06-06
    Vendor response : no response
    Vendor fix : no fix
    Vendor Sec report (vendor-sec@lst.de) : 2005-06-27
    Disclosure : 2005-07-04

    #####################
    Technical details :
    #####################

    Vulnerable code :
    -----------------

    In contrib/scripts/linki.py

    95 def czyjest ():
    96 if os.path.exists('/tmp/rmrmg_ekg_url'):
    97 wejsc= open ('/tmp/rmrmg_ekg_url')
    98 file = wejsc.readlines()
    99 dlug=len(file)
    100 wejsc.close()
    101 #ekg.printf("generic", "liczność %d" %(dlug))
    102 return file
    103 else:
    104 return 0

    Then

    35 def handle_keypress(meta, key):
    36 if key == 269:
    37 ekg.printf("generic", "wciśnieto F5")
    38 nurl=czyjest()
    39 if nurl == 0:
    40 ekg.printf("generic", "nie ma zadnego adresu URL")
    41 else:
    42 dlug=len(nurl)
    43 if dlug == 1:
    44 ekg.printf("generic", "otwieram %s w nowej zakładce"
    %(nurl[0]))
    45 os.system("MozillaFirebird -remote
    'openURL(%s,new-tab)'" %(nurl[0]))
    46 os.system('rm /tmp/rmrmg_ekg_url')
    47 else:
    48 ekg.printf("generic", "linków mam %d" %(dlug))
    49 wielejest(nurl)
    50 ekg.printf("generic", "otwieram %s w nowej zakładce"
    %(nurl[0]))
    51 os.system("MozillaFirebird -remote 'openURL(%s,
    new-tab)'" %(nurl[0]))
    52 elif key == 270:
    53 ekg.printf("generic", "wcisnięto F6")
    54 nurl=czyjest()
    55 if nurl == 0:
    56 ekg.printf("generic", "nic nie moge skasować - nie
    mazadnego adresu URL")
    57 else:
    58 dlug=len(nurl)
    59 if dlug == 1:
    60 ekg.printf("generic", "kasuje adres %s" %(nurl[0]))

    61 os.system('rm /tmp/rmrmg_ekg_url')
    62 else:
    63 ekg.printf("generic", "jest wiele linków")
    64 wielejest(nurl)
    65 ekg.printf("generic", "kasuje pierwszy czyli:
    %s"%(nurl[0]))
    66 elif key == 271:
    67 ekg.printf("generic", "wcisnięto F7")
    68 nurl=czyjest()
    69 if nurl == 0:
    70 ekg.printf("generic", "nie ma zadnego adresu URL")
    71 else:
    72 dlug=len(nurl)
    73 if dlug == 1:
    74 ekg.printf("generic", "otwieram %s w nowym
    oknie"%(nurl[0]))
    75 os.system("MozillaFirebird %s" %(nurl[0]))
    76 os.system('rm /tmp/rmrmg_ekg_url')
    77 else:
    78 ekg.printf("generic", "linków mam %d" %(dlug))
    79 wielejest(nurl)
    80 ekg.printf("generic", "otwieram %s w nowym
    oknie"%(nurl[0]))
    81 elif key == 272:
    82 ekg.printf("generic", "wcisnięto F8")
    83 nurl=czyjest()
    84 ekg.printf("generic", "F5 - otwiera w nowej zakładce; F7
    wnowym oknie, a F6 kasuje, wszystko tyczy się pierwszej po zycji
    zlisty")
    85 if nurl == 0:
    86 ekg.printf("generic", "nie ma zadnego adresu URL")
    87 else:
    88 dlug=len(nurl)
    89 ekg.printf("generic", "linków mam %d oto one:" %(dlug))
    90 for po in nurl:
    91 ekg.printf("generic", "%s" %(po))
    92 return 1

    #########
    Related :
    #########

    Gentoo Bugs report : http://bugs.gentoo.org/show_bug.cgi?id=94172
    CVE : CAN-2005-1916

    #####################
    Credits :
    #####################

    Eric Romang (eromang@zataz.net - ZATAZ Audit)
    Thxs to Gentoo Security Team. (Taviso, jaervosz, solar, tigger, etc.)


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