Bug 1442099 (CVE-2017-7467)

Summary: CVE-2017-7467 minicom: Out of bounds write in vt100.c
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED WONTFIX QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: carnil, dkholia, msehnout, olysonek, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: minicom 2.7.1 Doc Type: If docs needed, set a value
Doc Text:
A buffer overflow flaw was found in the way minicom handled VT100 escape sequences. A malicious terminal device could potentially use this flaw to crash minicom, or execute arbitrary code in the context of the minicom process.
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-04-20 04:42:16 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1443129    
Bug Blocks: 1442106    

Description Adam Mariš 2017-04-13 13:55:51 UTC
A potentially exploitable out of bounds write vulnerability in vt100.c was found.

Vulnerable code:

static void (*vt_keyb)(int, int);/* Gets called for NORMAL/APPL switch. */
static void (*termout)(const char *, int);/* Gets called to output a string. */

static int escparms[8];         /* Cumulated escape sequence. */
static int ptr;                 /* Index into escparms array. */
static long vt_tabs[5];         /* Tab stops for max. 32*5 = 160 columns. */

//...

  /* See if a number follows */
  if (c >= '0' && c <= '9') {
    escparms[ptr] = 10*escparms[ptr] + c - '0';
    return;
  }
  /* Separation between numbers ? */
  if (c == ';') {
    if (ptr < 15)
      ptr++;
    return;
  }

With crafted input, attacker can write out of bounds of escparms array and could potentially overwrite ptr pointer.

Comment 1 Adam Mariš 2017-04-13 13:55:55 UTC
Acknowledgments:

Name: Alexander Peslyak (Openwall)

Comment 5 Dhiru Kholia 2017-04-18 14:12:59 UTC
Created minicom tracking bugs for this issue:

Affects: fedora-all [bug 1443129]

Comment 6 Dhiru Kholia 2017-04-18 14:17:49 UTC
Public via http://www.openwall.com/lists/oss-security/2017/04/18/5