Deep packet inspection naively scanning for potential
fragments of bash scripts being transferred ?
Karsten
Am Fri, Aug 27, 2021 at 12:32:09PM +0530 schrieb Ninad Shah:
> Date: Fri, 27 Aug 2021 12:32:09 +0530
> From: Ninad Shah <nshah.postgres@xxxxxxxxx>
> To: pgsql-general <pgsql-general@xxxxxxxxxxxxxxxxxxxx>
> Subject: Issue with a query while running on a remote host
>
> Hello All,
>
> While working with a PostgreSQL database, I came across an issue where data
> is not being fetched over the network.
>
> Version : PostgreSQL 11.10
> Operating system : RHEL 8.4
>
> *Issue description:*
>
> We tried to execute the below query on the database host using psql prompt,
> it works without any issue.
>
> select regexp_replace(state_cd, E'[\\n\\r]+', '', 'g' ) as state_cd,
> off_cd, user_cd, regexp_replace(user_name, E'[\\n\\r]+', '', 'g' ) as
> user_name, regexp_replace(desig_cd, E'[\\n\\r]+', '', 'g' ) as desig_cd,
> regexp_replace(user_id, E'[\\n\\r]+', '', 'g' ) as user_id,
> regexp_replace(user_pwd, E'[\\n\\r]+', '', 'g' ) as user_pwd,
> regexp_replace(phone_off, E'[\\n\\r]+', '', 'g' ) as phone_off, mobile_no,
> regexp_replace(email_id, E'[\\n\\r]+', '', 'g' ) as email_id,
> regexp_replace(user_catg, E'[\\n\\r]+', '', 'g' ) as user_catg,
> regexp_replace(status, E'[\\n\\r]+', '', 'g' ) as status, created_by,
> created_dt, aadhaar, op_dt, regexp_replace(login_ipaddress, E'[\\n\\r]+',
> '', 'g' ) as login_ipaddress, regexp_replace(forget_password, E'[\\n\\r]+',
> '', 'g' ) as forget_password, regexp_replace(newuser_change_password,
> E'[\\n\\r]+', '', 'g' ) as newuser_change_password from tm_user_info
> where ( user_cd >= 1068540014 ) AND ( user_cd <= 2137079303 ) ;
>
> While trying to execute the same query over the network using psql prompt,
> the execution doesn't finish.
>
> *My Analysis:*
>
> By digging further, we came to see that a specific record was causing the
> issue, and by further analysis, we saw that the records that contain a
> specific string("*bash@*") in the column user_id are not being fetched over
> the network.
>
> To confirm that, we also changed some records manually by creating a test
> table. And, we were able to reproduce the issue.
>
> vow4_xdb=# select * from vahan4.test_tbl where user_cd =2106011301;
> .
> .
>
> But, this issue doesn't occur if we try to fetch on the database host or
> via PgAdmin4. In such cases, we get the record in a few milliseconds.
>
> *Surprisingly, this table has only one record.*
>
> There is no table/row-level lock found here.
>
>
> *Table definition:-*
> Table "test_tbl"
> Column | Type | Collation |
> Nullable | Default | Storage | Stats targe
> t | Description
> -------------------------+-----------------------------+-----------+----------+---------+----------+------------
> --+-------------
> state_cd | character varying(2) | | not
> null | | extended |
> |
> off_cd | numeric(5,0) | | not
> null | | main |
> |
> user_cd | numeric(10,0) | | not
> null | | main |
> |
> user_name | character varying(99) | | not
> null | | extended |
> |
> desig_cd | character varying(10) | | not
> null | | extended |
> |
> user_id | character varying(20) | | not
> null | | extended |
> |
> user_pwd | character varying(100) | | not
> null | | extended |
> |
> phone_off | character varying(20) | |
> | | extended |
> |
> mobile_no | numeric(10,0) | | not
> null | | main |
> |
> email_id | character varying(50) | |
> | | extended |
> |
> user_catg | character varying(1) | | not
> null | | extended |
> |
> status | character varying(1) | | not
> null | | extended |
> |
> created_by | numeric(10,0) | | not
> null | | main |
> |
> created_dt | date | | not
> null | | plain |
> |
> aadhaar | numeric(12,0) | |
> | | main |
> |
> op_dt | timestamp without time zone | | not
> null | now() | plain |
> |
> login_ipaddress | character varying(20) | |
> | | extended |
> |
> forget_password | character varying(1) | |
> | | extended |
> |
> newuser_change_password | character varying(1) | |
> | | extended |
> |
> Indexes:
> "tm_user_info_pkey" PRIMARY KEY, btree (user_cd)
> "idx_tm_user_info_user_id" UNIQUE, btree (user_id)
> Replica Identity: FULL
>
>
> *Record with an issue:-*
> state_cd|off_cd|user_cd|user_name|desig_cd|user_id|user_pwd|phone_off|mobile_no|email_id|user_catg|status|created_by|created_dt|aadhaar|op_dt|login_ipaddress|forget_password|newuser_change_password
> HR|31|2106011301|SUBASH AUTO HOUSE|DS|subash@123
> |c22d1779437117852ffcdeb7e9c689f41c502a1dae2687b8845a33bb892f3b66||9255561872|
> skpanwar2311@xxxxxxxxx|B|D|2006078673|2021-01-04|0|2021-01-04
> 14:30:27.715728||N|F
> (1 row)
>
>
> Can anyone help me out here?
>
>
> Regards,
> Ninad Shah
--
GPG 40BE 5B0E C98E 1713 AFA6 5BC0 3BEA AC80 7D4F C89B
