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Date: Mon, 5 Dec 2016 16:18:37 -0600
From: Tyler Hicks <tyhicks@...onical.com>
To: "Steven M. Schweda" <sms@...inode.info>, oss-security@...ts.openwall.com
Cc: security@...ntu.com, Info-ZIP-Dev@...tley.com
Subject: Re: CVE Request: Info-Zip zipinfo buffer overflow
On 12/05/2016 03:50 PM, Steven M. Schweda wrote:
> From: Tyler Hicks <tyhicks@...onical.com>
>
> Thanks for the (thorough, helpful) report.
I appreciate it but Alexis deserves most of the credit.
>
>> 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):
Thanks for the quick fix. Is there a public code repository available so
that we can reference a specific commit that fixes this issue?
>
> 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.)
Nope. As you probably noticed, MITRE just assigned a CVE. It likely
helped that you confirmed the issue. Thanks again!
Tyler
>
> ------------------------------------------------------------------------
>
> Steven M. Schweda sms@...inode-info
>
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