Tcpdump tries to creates "tcpdump" user and "tcpdump" group without checking whether they exist beforehand

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux (RHEL) 7
  • tcpdump 4.5.1
  • tcpdump 4.9.0
  • tcpdump 4.9.2

Issue

During an installation of tcpdump, it attempts to create tcpdump user and group without previously checking if that group/user already exist. That behaviour raises alerts in /var/log/audit/audit.log.

Resolution

Update to tcpdump-4.9.2-4.el7 released with Advisory RHBA-2019:2342 or newer.

Root Cause

The tcpdump package tries to create tcpdump user and group unconditionally, without checking whether they already exist. This bug is fixed in tcpdump-4.9.2-4.el7 and newer.

Diagnostic Steps

To reproduce the issue upgrade thetpcdump package from a previous version while having auditing enabled. Auditing is enabled in RHEL 7 by default.

  • To perform the upgrade execute the following command:

    # yum upgrade tcpdump
    
  • Actual results seen in /var/log/audit/audit.log:

    type=ADD_GROUP msg=audit(1547033150.379:79791): pid=6469 uid=0 auid=0 ses=3832 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 msg='op=add-group acct="tcpdump" exe="/usr/sbin/groupadd" hostname=host.example.com addr=? terminal=pts/0 res=failed'
    type=ADD_USER msg=audit(1547033233.280:79798): pid=7841 uid=0 auid=0 ses=3832 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 msg='op=add-user acct="tcpdump" exe="/usr/sbin/useradd" hostname=host.example.com addr=? terminal=pts/0 res=failed'
    
  • Component
  • rpm

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