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Date: Mon, 5 Dec 2016 15:50:41 -0600 (CST)
From: "Steven M. Schweda" <sms@...inode.info>
To: tyhicks@...onical.com, oss-security@...ts.openwall.com
Cc: security@...ntu.com, Info-ZIP-Dev@...tley.com
Subject: CVE Request: Info-Zip zipinfo buffer overflow

From: Tyler Hicks <tyhicks@...onical.com>

   Thanks for the (thorough, helpful) report.

> Alexis Vanden Eijnde has discovered a zipinfo buffer overflow and
> reported it here:
> 
>   https://launchpad.net/bugs/1643750
> 
> It is very similar to, but different than, this `unzip -l` crasher:
> 
>   http://www.openwall.com/lists/oss-security/2014/11/03/5

   It is.  And the easy fix is also very similar (and should appear in
the next UnZip release, version 6.1e beta):

ALP $ gdiff zipinfo.c;39 zipinfo.c
2568c2568,2579
<         sprintf(&methbuf[1], "%03u", G.crec.compression_method);
---
>         /* 2016-12-05 SMS.
>          * https://launchpad.net/bugs/1643750
>          * Unexpectedly large compression methods overflow
>          * &methbuf[].  Use the old, three-digit decimal format
>          * for values which fit.  Otherwise, sacrifice the "u",
>          * and use four-digit hexadecimal.
>          */
>         if (G.crec.compression_method <= 999) {
>             sprintf( &methbuf[ 1], "%03u", G.crec.compression_method);
>         } else {
>             sprintf( &methbuf[ 0], "%04X", G.crec.compression_method);
>         }

   Typical output (pre-release UnZip 6.1e beta, with some minor,
unrelated report format changes from UnZip 6.0):

   Old:

ALP $ unzip6l -Z PoZ.zip
Archive:  ALP$DKC0:[UTILITY.SOURCE.ZIP.test_mthd_ovflo]PoZ.zip;1
Zip file size: 154 bytes, number of entries: 1
-rw-rw-r--  3.0 unx        2 tx u65535 16-Nov-21 19:07 a
                                ^^^^^^
1 file, 2 bytes uncompressed, 2 bytes compressed:  0.0%

   New/next:

ALP $ unzipx -Z PoZ.zip
Archive:  ALP$DKC0:[UTILITY.SOURCE.ZIP.test_mthd_ovflo]PoZ.zip;1
Archive size: 154 bytes; Members: 1
-rw-rw-r--  3.0 unx        2 tx FFFF 16-Nov-21 19:07 a
                                ^^^^
Members: 1; Bytes uncompressed: 2, compressed: 2, 0.0%
Directories: 0, Files: 1, Links: 0

> The zipinfo buffer overflow occurs due to a flaw in zipinfo.c's
> zi_short() function:
> [...]

   Yeah.  We should have noticed this whan the "unzip -l" complaint was
made.

> Please assign a CVE. Also, consider assigning a CVE to the related
> `unzip -l` issue from 2014. Thank you!

   Is that something I should do?  (I normally get reports with CVEs; I
have never created one.)

------------------------------------------------------------------------

   Steven M. Schweda               sms@...inode-info

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